Create delegates and empty instances in DeepCloner

Fixes: #9030

model/build-processor/src/main/java/org/keycloak/models/map/processor/AbstractGenerateEntityImplementationsProcessor.java

@@ -45,13 +45,20 @@ import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+import javax.annotation.processing.SupportedSourceVersion;
+import javax.lang.model.SourceVersion;
 import static org.keycloak.models.map.processor.FieldAccessorType.GETTER;
 import static org.keycloak.models.map.processor.Util.getGenericsDeclaration;
 import static org.keycloak.models.map.processor.Util.isMapType;
 
+@SupportedSourceVersion(SourceVersion.RELEASE_8)
 public abstract class AbstractGenerateEntityImplementationsProcessor extends AbstractProcessor {
 
     protected static final String FQN_DEEP_CLONER = "org.keycloak.models.map.common.DeepCloner";
+    protected static final String FQN_ENTITY_FIELD = "org.keycloak.models.map.common.EntityField";
+    protected static final String FQN_HAS_ENTITY_FIELD_DELEGATE = "org.keycloak.models.map.common.delegate.HasEntityFieldDelegate";
+    protected static final String FQN_ENTITY_FIELD_DELEGATE = "org.keycloak.models.map.common.delegate.EntityFieldDelegate";
+
     protected Elements elements;
     protected Types types;
 
@@ -100,16 +107,19 @@ public abstract class AbstractGenerateEntityImplementationsProcessor extends Abs
 //          );
     }
 
+    protected Stream<ExecutableElement> getAllAbstractMethods(TypeElement e) {
+        return elements.getAllMembers(e).stream()
+          .filter(el -> el.getKind() == ElementKind.METHOD)
+          .filter(el -> el.getModifiers().contains(Modifier.ABSTRACT))
+          .filter(ExecutableElement.class::isInstance)
+          .map(ExecutableElement.class::cast);
+    }
+
     protected Map<String, HashSet<ExecutableElement>> methodsPerAttributeMapping(TypeElement e) {
-        final List<? extends Element> allMembers = elements.getAllMembers(e);
+        Map<String, HashSet<ExecutableElement>> methodsPerAttribute = getAllAbstractMethods(e)
-        Map<String, HashSet<ExecutableElement>> methodsPerAttribute = allMembers.stream()
+          .filter(Util::isNotIgnored)
-                .filter(el -> el.getKind() == ElementKind.METHOD)
+          .filter(ee -> ! (ee.getReceiverType() instanceof NoType))
-                .filter(el -> el.getModifiers().contains(Modifier.ABSTRACT))
+          .collect(Collectors.toMap(this::determineAttributeFromMethodName, v -> new HashSet<>(Arrays.asList(v)), (a,b) -> { a.addAll(b); return a; }));
-                .filter(Util::isNotIgnored)
-                .filter(ExecutableElement.class::isInstance)
-                .map(ExecutableElement.class::cast)
-                .filter(ee -> ! (ee.getReceiverType() instanceof NoType))
-                .collect(Collectors.toMap(this::determineAttributeFromMethodName, v -> new HashSet(Arrays.asList(v)), (a, b) -> { a.addAll(b); return a; }));
 
         // Merge plurals with singulars
         methodsPerAttribute.keySet().stream()
@@ -129,7 +139,7 @@ public abstract class AbstractGenerateEntityImplementationsProcessor extends Abs
         FORBIDDEN_PREFIXES.put("delete", "remove");
     }
 
-    private String determineAttributeFromMethodName(ExecutableElement e) {
+    protected String determineAttributeFromMethodName(ExecutableElement e) {
         Name name = e.getSimpleName();
         Matcher m = BEAN_NAME.matcher(name.toString());
         if (m.matches()) {

model/build-processor/src/main/java/org/keycloak/models/map/processor/GenerateEntityImplementationsProcessor.java

@@ -17,12 +17,12 @@
 package org.keycloak.models.map.processor;
 
 import org.keycloak.models.map.annotations.GenerateEntityImplementations;
+
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
-import java.util.Objects;
 import java.util.stream.Collectors;
 import javax.annotation.processing.SupportedAnnotationTypes;
 import javax.annotation.processing.SupportedSourceVersion;
@@ -47,6 +47,7 @@ import java.util.Optional;
 import java.util.TreeSet;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import java.util.stream.Stream;
 import javax.lang.model.element.VariableElement;
 import javax.lang.model.type.TypeKind;
 
@@ -58,30 +59,36 @@ import javax.lang.model.type.TypeKind;
 @SupportedSourceVersion(SourceVersion.RELEASE_8)
 public class GenerateEntityImplementationsProcessor extends AbstractGenerateEntityImplementationsProcessor {
 
-    private Collection<String> cloners = new TreeSet<>();
+    private final Collection<String> autogenerated = new TreeSet<>();
 
     private final Generator[] generators = new Generator[] {
         new ClonerGenerator(),
         new DelegateGenerator(),
         new FieldsGenerator(),
-        new ImplGenerator()
+        new FieldDelegateGenerator(),
+        new ImplGenerator(),
     };
 
     @Override
     protected void afterAnnotationProcessing() {
-        if (! cloners.isEmpty()) {
+        if (! autogenerated.isEmpty()) {
             try {
                 JavaFileObject file = processingEnv.getFiler().createSourceFile("org.keycloak.models.map.common.AutogeneratedCloners");
                 try (PrintWriter pw = new PrintWriterNoJavaLang(file.openWriter())) {
                     pw.println("package org.keycloak.models.map.common;");
 
-                    pw.println("import org.keycloak.models.map.common.DeepCloner.Cloner;");
+                    pw.println("import " + FQN_DEEP_CLONER + ".Cloner;");
+                    pw.println("import " + FQN_DEEP_CLONER + ".DelegateCreator;");
+                    pw.println("import " + FQN_DEEP_CLONER + ".EntityFieldDelegateCreator;");
                     pw.println("// DO NOT CHANGE THIS CLASS, IT IS GENERATED AUTOMATICALLY BY " + GenerateEntityImplementationsProcessor.class.getSimpleName());
                     pw.println("public final class AutogeneratedCloners {");
                     pw.println("    public static final java.util.Map<Class<?>, Cloner<?>> CLONERS_WITH_ID = new java.util.HashMap<>();");
                     pw.println("    public static final java.util.Map<Class<?>, Cloner<?>> CLONERS_WITHOUT_ID = new java.util.HashMap<>();");
+                    pw.println("    public static final java.util.Map<Class<?>, DelegateCreator<?>> DELEGATE_CREATORS = new java.util.HashMap<>();");
+                    pw.println("    public static final java.util.Map<Class<?>, EntityFieldDelegateCreator<?>> ENTITY_FIELD_DELEGATE_CREATORS = new java.util.HashMap<>();");
+                    pw.println("    public static final java.util.Map<Class<?>, Object> EMPTY_INSTANCES = new java.util.HashMap<>();");
                     pw.println("    static {");
-                    cloners.forEach(pw::println);
+                    autogenerated.forEach(pw::println);
                     pw.println("    }");
                     pw.println("}");
                 }
@@ -111,6 +118,7 @@ public class GenerateEntityImplementationsProcessor extends AbstractGenerateEnti
     }
 
     private class FieldsGenerator implements Generator {
+
         @Override
         public void generate(TypeElement e) throws IOException {
             Map<String, HashSet<ExecutableElement>> methodsPerAttribute = methodsPerAttributeMapping(e);
@@ -131,14 +139,104 @@ public class GenerateEntityImplementationsProcessor extends AbstractGenerateEnti
                     pw.println("package " + packageName + ";");
                 }
 
-                pw.println("public enum " + mapSimpleFieldsClassName + " {");
+                pw.println("public enum " + mapSimpleFieldsClassName + " implements " + FQN_ENTITY_FIELD + "<" + className + "> {");
                 methodsPerAttribute.keySet().stream()
                   .sorted(NameFirstComparator.ID_INSTANCE)
-                  .map(GenerateEntityImplementationsProcessor::toEnumConstant)
+                  .forEach(key -> {
-                  .forEach(key -> pw.println("    " + key + ","));
+                      pw.println("    " + toEnumConstant(key) + " {");
+                      printEntityFieldMethods(pw, className, key, methodsPerAttribute.get(key));
+                      pw.println("    },");
+                  });
                 pw.println("}");
             }
         }
+
+        private void printEntityFieldMethods(PrintWriter pw, String className, String fieldName, HashSet<ExecutableElement> methods) {
+            TypeMirror fieldType = determineFieldType(fieldName, methods);
+            pw.println("        public static final String FIELD_NAME = \"" + fieldName + "\";");
+            pw.println("        public static final String FIELD_NAME_DASHED = \"" + fieldName.replaceAll("([^_A-Z])([A-Z])", "$1-$2").toLowerCase() + "\";");
+            pw.println("        @SuppressWarnings(\"unchecked\") @Override public Class<?> getFieldClass() {");
+            pw.println("            return " + types.erasure(fieldType) + ".class;");
+            pw.println("        }");
+            pw.println("        @Override public String getName() {");
+            pw.println("            return FIELD_NAME;");
+            pw.println("        }");
+            pw.println("        @Override public String getNameDashed() {");
+            pw.println("            return FIELD_NAME_DASHED;");
+            pw.println("        }");
+
+            FieldAccessorType.getMethod(FieldAccessorType.COLLECTION_ADD, methods, fieldName, types, fieldType).ifPresent(method -> {
+                TypeMirror firstParameterType = method.getParameters().get(0).asType();
+                pw.println("        @SuppressWarnings(\"unchecked\") @Override public Class<?> getCollectionElementClass() {");
+                pw.println("            return " + types.erasure(firstParameterType) + ".class;");
+                pw.println("        }");
+            });
+            
+            FieldAccessorType.getMethod(FieldAccessorType.MAP_ADD, methods, fieldName, types, fieldType).ifPresent(method -> {
+                TypeMirror firstParameterType = method.getParameters().get(0).asType();
+                TypeMirror secondParameterType = method.getParameters().get(1).asType();
+                pw.println("        @SuppressWarnings(\"unchecked\") @Override public Class<?> getMapKeyClass() {");
+                pw.println("            return " + types.erasure(firstParameterType) + ".class;");
+                pw.println("        }");
+                pw.println("        @SuppressWarnings(\"unchecked\") @Override public Class<?> getMapValueClass() {");
+                pw.println("            return " + types.erasure(secondParameterType) + ".class;");
+                pw.println("        }");
+            });
+            
+            for (ExecutableElement ee : methods) {
+                FieldAccessorType fat = FieldAccessorType.determineType(ee, fieldName, types, fieldType);
+                printMethodBody(pw, fat, ee, className, fieldType);
+            }
+        }
+
+        private void printMethodBody(PrintWriter pw, FieldAccessorType accessorType, ExecutableElement method, String className, TypeMirror fieldType) {
+            TypeMirror firstParameterType = method.getParameters().isEmpty()
+              ? types.getNullType()
+              : method.getParameters().get(0).asType();
+
+            switch (accessorType) {
+                case GETTER:
+                    pw.println("        @SuppressWarnings(\"unchecked\") @Override public " + method.getReturnType() + " get(" + className + " e) {");
+                    pw.println("            return (" + fieldType + ") e." + method.getSimpleName() + "();");
+                    pw.println("        }");
+                    return;
+                case SETTER:
+                    pw.println("        @SuppressWarnings(\"unchecked\") @Override public <T> void set(" + className + " e, T value) {");
+                    pw.println("            e." + method.getSimpleName() + "((" + firstParameterType + ") value);");
+                    pw.println("        }");
+                    return;
+                case COLLECTION_ADD:
+                    pw.println("        @SuppressWarnings(\"unchecked\") @Override public <T> void collectionAdd(" + className + " e, T value) {");
+                    pw.println("            e." + method.getSimpleName() + "((" + firstParameterType + ") value);");
+                    pw.println("        }");
+                    return;
+                case COLLECTION_DELETE:
+                    String returnType = method.getReturnType().getKind() == TypeKind.VOID ? "Void" : method.getReturnType().toString();
+                    TypeElement fieldTypeElement = elements.getTypeElement(types.erasure(fieldType).toString());
+                    if (Util.isMapType(fieldTypeElement)) {
+                        pw.println("        @SuppressWarnings(\"unchecked\") @Override public <K> " + returnType + " mapRemove(" + className + " e, K p0) {");
+                    } else {
+                        pw.println("        @SuppressWarnings(\"unchecked\") @Override public <T> " + returnType + " collectionRemove(" + className + " e, T p0) {");
+                    }
+                    if (method.getReturnType().getKind() == TypeKind.VOID) {
+                        pw.println("            e." + method.getSimpleName() + "((" + firstParameterType + ") p0); return null;");
+                    } else {
+                        pw.println("            return (" + method.getReturnType() + ") e." + method.getSimpleName() + "((" + firstParameterType + ") p0);");
+                    }
+                    pw.println("        }");
+                    return;
+                case MAP_ADD:
+                    TypeMirror secondParameterType = method.getParameters().get(1).asType();
+                    pw.println("        @SuppressWarnings(\"unchecked\") @Override public <K, T> void mapPut(" + className + " e, K key, T value) {");
+                    pw.println("            e." + method.getSimpleName() + "((" + firstParameterType + ") key, (" + secondParameterType + ") value);");
+                    pw.println("        }");
+                    return;
+                case MAP_GET:
+                    pw.println("        @SuppressWarnings(\"unchecked\") @Override public <K> " + method.getReturnType() + " mapGet(" + className + " e, K key) {");
+                    pw.println("            return (" + method.getReturnType() + ") e." + method.getSimpleName() + "((" + firstParameterType + ") key);");
+                    pw.println("        }");
+            }
+        }
     }
 
     private class ImplGenerator implements Generator {
@@ -151,7 +249,7 @@ public class GenerateEntityImplementationsProcessor extends AbstractGenerateEnti
             if (parentTypeElement == null) {
                 return;
             }
-            final List<? extends Element> allMembers = elements.getAllMembers(parentTypeElement);
+            final List<? extends Element> allParentMembers = elements.getAllMembers(parentTypeElement);
             String className = e.getQualifiedName().toString();
             String packageName = null;
             int lastDot = className.lastIndexOf('.');
@@ -162,8 +260,8 @@ public class GenerateEntityImplementationsProcessor extends AbstractGenerateEnti
             String simpleClassName = className.substring(lastDot + 1);
             String mapImplClassName = className + "Impl";
             String mapSimpleClassName = simpleClassName + "Impl";
-            boolean hasId = methodsPerAttribute.containsKey("Id") || allMembers.stream().anyMatch(el -> "getId".equals(el.getSimpleName().toString()));
+            boolean hasId = methodsPerAttribute.containsKey("Id") || allParentMembers.stream().anyMatch(el -> "getId".equals(el.getSimpleName().toString()));
-            boolean hasDeepClone = allMembers.stream().filter(el -> el.getKind() == ElementKind.METHOD).anyMatch(el -> "deepClone".equals(el.getSimpleName().toString()));
+            boolean hasDeepClone = allParentMembers.stream().filter(el -> el.getKind() == ElementKind.METHOD).anyMatch(el -> "deepClone".equals(el.getSimpleName().toString()));
             boolean needsDeepClone = fieldGetters(methodsPerAttribute)
               .map(ExecutableElement::getReturnType)
               .anyMatch(fieldType -> ! isKnownCollectionOfImmutableFinalTypes(fieldType) && ! isImmutableFinalType(fieldType));
@@ -180,7 +278,7 @@ public class GenerateEntityImplementationsProcessor extends AbstractGenerateEnti
                 pw.println("public class " + mapSimpleClassName + (an.inherits().isEmpty() ? "" : " extends " + an.inherits()) + " implements " + className + " {");
 
                 // Constructors
-                allMembers.stream()
+                allParentMembers.stream()
                   .filter(ExecutableElement.class::isInstance)
                   .map(ExecutableElement.class::cast)
                   .filter((ExecutableElement ee) -> ee.getKind() == ElementKind.CONSTRUCTOR)
@@ -222,7 +320,7 @@ public class GenerateEntityImplementationsProcessor extends AbstractGenerateEnti
                   + ";");
                 pw.println("    }");
                 pw.println("    @Override public int hashCode() {");
-                pw.println("        return " 
+                pw.println("        return "
                   + (hasId
                     ? "(getId() == null ? super.hashCode() : getId().hashCode())"
                     : "Objects.hash("
@@ -261,12 +359,7 @@ public class GenerateEntityImplementationsProcessor extends AbstractGenerateEnti
 
                     for (ExecutableElement method : methods) {
                         FieldAccessorType fat = FieldAccessorType.determineType(method, me.getKey(), types, fieldType);
-                        Optional<ExecutableElement> parentMethod = allMembers.stream()
+                        Optional<ExecutableElement> parentMethod = Util.findParentMethodImplementation(allParentMembers, method);
-                          .filter(ExecutableElement.class::isInstance)
-                          .map(ExecutableElement.class::cast)
-                          .filter(ee -> Objects.equals(ee.toString(), method.toString()))
-                          .filter((ExecutableElement ee) ->  ! ee.getModifiers().contains(Modifier.ABSTRACT))
-                          .findAny();
 
                         if (parentMethod.isPresent()) {
                             processingEnv.getMessager().printMessage(Kind.OTHER, "Method " + method + " is declared in a parent class.", method);
@@ -275,6 +368,44 @@ public class GenerateEntityImplementationsProcessor extends AbstractGenerateEnti
                         }
                     }
                 });
+
+                // Read-only class overrides setters to be no-op
+                pw.println("    public static class Empty " + (an.inherits().isEmpty() ? "" : " extends " + an.inherits()) + " implements " + className + " {");
+                pw.println("        public static final Empty INSTANCE = new Empty();");
+                methodsPerAttribute.entrySet().stream().sorted(Comparator.comparing(Map.Entry::getKey, NameFirstComparator.ID_INSTANCE))
+                  .map(Map.Entry::getValue)
+                  .flatMap(Collection::stream)
+                  .forEach(ee -> {
+                    pw.println("        @Override "
+                      + ee.getModifiers().stream().filter(m -> m != Modifier.ABSTRACT).map(Object::toString).collect(Collectors.joining(" "))
+                      + " " + ee.getReturnType()
+                      + " " + ee.getSimpleName()
+                      + "(" + methodParameters(ee.getParameters()) + ") {");
+                    if (ee.getReturnType().getKind() == TypeKind.VOID) {
+                        pw.println("        }");
+                    } else {
+                        pw.println("            return null;");
+                        pw.println("        }");
+                    }
+                });
+                elements.getAllMembers(e).stream()
+                  .filter(ee -> ee.getSimpleName().contentEquals("isUpdated"))
+                  .filter(ExecutableElement.class::isInstance)
+                  .map(ExecutableElement.class::cast)
+                  .filter(ee -> ee.getReturnType().getKind() == TypeKind.BOOLEAN)
+                  .forEach(ee -> {
+                    pw.println("        @Override "
+                      + ee.getModifiers().stream().filter(m -> m != Modifier.ABSTRACT).map(Object::toString).collect(Collectors.joining(" "))
+                      + " " + ee.getReturnType()
+                      + " " + ee.getSimpleName()
+                      + "(" + methodParameters(ee.getParameters()) + ") {");
+                    pw.println("            return false;");
+                    pw.println("        }");
+                });
+                pw.println("    }");
+
+                autogenerated.add("        EMPTY_INSTANCES.put(" + className + ".class, " + mapImplClassName + ".Empty.INSTANCE);");
+
                 pw.println("}");
             }
         }
@@ -343,6 +474,122 @@ public class GenerateEntityImplementationsProcessor extends AbstractGenerateEnti
         }
     }
 
+    private class FieldDelegateGenerator implements Generator {
+
+        @Override
+        public void generate(TypeElement e) throws IOException {
+            Map<String, HashSet<ExecutableElement>> methodsPerAttribute = methodsPerAttributeMapping(e);
+            String className = e.getQualifiedName().toString();
+            String packageName = null;
+            int lastDot = className.lastIndexOf('.');
+            if (lastDot > 0) {
+                packageName = className.substring(0, lastDot);
+            }
+
+            String simpleClassName = className.substring(lastDot + 1);
+            String mapClassName = className + "FieldDelegate";
+            String mapSimpleClassName = simpleClassName + "FieldDelegate";
+            String fieldsClassName = className + "Fields";
+
+            GenerateEntityImplementations an = e.getAnnotation(GenerateEntityImplementations.class);
+            TypeElement parentTypeElement = elements.getTypeElement((an.inherits() == null || an.inherits().isEmpty()) ? "void" : an.inherits());
+            if (parentTypeElement == null) {
+                return;
+            }
+
+            JavaFileObject file = processingEnv.getFiler().createSourceFile(mapClassName);
+            IdentityHashMap<ExecutableElement, String> m2field = new IdentityHashMap<>();
+            methodsPerAttribute.forEach((f, s) -> s.forEach(m -> m2field.put(m, f)));   // Create reverse map
+            try (PrintWriter pw = new PrintWriterNoJavaLang(file.openWriter())) {
+                if (packageName != null) {
+                    pw.println("package " + packageName + ";");
+                }
+
+                pw.println("public class " + mapSimpleClassName + (an.inherits().isEmpty() ? "" : " extends " + an.inherits()) + " implements " + className + ", " + FQN_HAS_ENTITY_FIELD_DELEGATE + "<" + className + ">" + " {");
+                pw.println("    private final " + FQN_ENTITY_FIELD_DELEGATE + "<" + className + "> entityFieldDelegate;");
+                pw.println("    public " + mapSimpleClassName + "(" + FQN_ENTITY_FIELD_DELEGATE + "<" + className + "> entityFieldDelegate) {");
+                pw.println("        this.entityFieldDelegate = entityFieldDelegate;");
+                pw.println("    }");
+                pw.println("    public " + FQN_ENTITY_FIELD_DELEGATE + "<" + className + "> getEntityFieldDelegate() {");
+                pw.println("        return this.entityFieldDelegate;");
+                pw.println("    }");
+
+                getAllAbstractMethods(e)
+                  .forEach(ee -> {
+                      String originalField = m2field.get(ee);
+                      if (originalField == null) {
+                          return;
+                      }
+                      TypeMirror fieldType = determineFieldType(originalField, methodsPerAttribute.get(originalField));
+                      String field = fieldsClassName + "." + toEnumConstant(originalField);
+
+                      if (ee.getReturnType().getKind() == TypeKind.BOOLEAN && "isUpdated".equals(ee.getSimpleName().toString())) {
+                          pw.println("        return entityFieldDelegate.isUpdated();");
+                          pw.println("    }");
+                      } else if (ee.getReturnType().getKind() == TypeKind.VOID && "clearUpdatedFlag".equals(ee.getSimpleName().toString())) {
+                          pw.println("        return entityFieldDelegate.clearUpdatedFlag();");
+                          pw.println("    }");
+                      } else {
+                          FieldAccessorType fat = FieldAccessorType.determineType(ee, originalField, types, fieldType);
+                          printMethodBody(pw, fat, ee, field, fieldType);
+                      }
+                  });
+
+                autogenerated.add("        ENTITY_FIELD_DELEGATE_CREATORS.put(" + className + ".class, (EntityFieldDelegateCreator<" + className + ">) " + mapClassName + "::new);");
+
+                pw.println("}");
+            }
+        }
+
+        private boolean printMethodBody(PrintWriter pw, FieldAccessorType accessorType, ExecutableElement method, String fieldName, TypeMirror fieldType) {
+            TypeMirror firstParameterType = method.getParameters().isEmpty()
+              ? types.getNullType()
+              : method.getParameters().get(0).asType();
+
+            switch (accessorType) {
+                case GETTER:
+                    pw.println("    @SuppressWarnings(\"unchecked\") @Override public " + method.getReturnType() + " " + method + " {");
+                    pw.println("        return (" + fieldType + ") entityFieldDelegate.get(" + fieldName + ");");
+                    pw.println("    }");
+                    return true;
+                case SETTER:
+                    pw.println("    @SuppressWarnings(\"unchecked\") @Override public " + method.getReturnType() + " " + method.getSimpleName() + "(" + firstParameterType + " p0) {");
+                    pw.println("        entityFieldDelegate.set(" + fieldName + ", p0);");
+                    pw.println("    }");
+                    return true;
+                case COLLECTION_ADD:
+                    pw.println("    @SuppressWarnings(\"unchecked\") @Override public " + method.getReturnType() + " " + method.getSimpleName() + "(" + firstParameterType + " p0) {");
+                    pw.println("        entityFieldDelegate.collectionAdd(" + fieldName + ", p0);");
+                    pw.println("    }");
+                    return true;
+                case COLLECTION_DELETE:
+                    pw.println("    @SuppressWarnings(\"unchecked\") @Override public " + method.getReturnType() + " " + method.getSimpleName() + "(" + firstParameterType + " p0) {");
+                    TypeElement fieldTypeElement = elements.getTypeElement(types.erasure(fieldType).toString());
+                    String removeMethod = Util.isMapType(fieldTypeElement) ? "mapRemove" : "collectionRemove";
+                    if (method.getReturnType().getKind() == TypeKind.VOID) {
+                        pw.println("        entityFieldDelegate." + removeMethod + "(" + fieldName + ", p0);");
+                    } else {
+                        pw.println("        return (" + method.getReturnType() + ") entityFieldDelegate." + removeMethod + "(" + fieldName + ", p0);");
+                    }
+                    pw.println("    }");
+                    return true;
+                case MAP_ADD:
+                    TypeMirror secondParameterType = method.getParameters().get(1).asType();
+                    pw.println("    @SuppressWarnings(\"unchecked\") @Override public " + method.getReturnType() + " " + method.getSimpleName() + "(" + firstParameterType + " p0, " + secondParameterType + " p1) {");
+                    pw.println("        entityFieldDelegate.mapPut(" + fieldName + ", p0, p1);");
+                    pw.println("    }");
+                    return true;
+                case MAP_GET:
+                    pw.println("    @SuppressWarnings(\"unchecked\") @Override public " + method.getReturnType() + " " + method.getSimpleName() + "(" + firstParameterType + " p0) {");
+                    pw.println("        return (" + method.getReturnType() + ") entityFieldDelegate.mapGet(" + fieldName + ", p0);");
+                    pw.println("    }");
+                    return true;
+            }
+
+            return false;
+        }
+    }
+
     private class DelegateGenerator implements Generator {
         @Override
         public void generate(TypeElement e) throws IOException {
@@ -364,7 +611,6 @@ public class GenerateEntityImplementationsProcessor extends AbstractGenerateEnti
             if (parentTypeElement == null) {
                 return;
             }
-            final List<? extends Element> allMembers = elements.getAllMembers(e);
 
             JavaFileObject file = processingEnv.getFiler().createSourceFile(mapClassName);
             IdentityHashMap<ExecutableElement, String> m2field = new IdentityHashMap<>();
@@ -380,11 +626,7 @@ public class GenerateEntityImplementationsProcessor extends AbstractGenerateEnti
                 pw.println("        this.delegateProvider = delegateProvider;");
                 pw.println("    }");
 
-                allMembers.stream()
+                getAllAbstractMethods(e)
-                  .filter(m -> m.getKind() == ElementKind.METHOD)
-                  .filter(ExecutableElement.class::isInstance)
-                  .map(ExecutableElement.class::cast)
-                  .filter(ee -> ee.getModifiers().contains(Modifier.ABSTRACT))
                   .forEach(ee -> {
                       pw.println("    @Override "
                         + ee.getModifiers().stream().filter(m -> m != Modifier.ABSTRACT).map(Object::toString).collect(Collectors.joining(" "))
@@ -396,11 +638,15 @@ public class GenerateEntityImplementationsProcessor extends AbstractGenerateEnti
                       if (ee.getReturnType().getKind() == TypeKind.BOOLEAN && "isUpdated".equals(ee.getSimpleName().toString())) {
                           pw.println("        return delegateProvider.isUpdated();");
                       } else if (ee.getReturnType().getKind() == TypeKind.VOID) {  // write operation
-                          pw.println("        delegateProvider.getDelegate(false, " + field + ")." + ee.getSimpleName() + "("
+                          pw.println("        delegateProvider.getDelegate(false, "
+                            + Stream.concat(Stream.of(field), ee.getParameters().stream().map(VariableElement::getSimpleName)).collect(Collectors.joining(", "))
+                            + ")." + ee.getSimpleName() + "("
                             + ee.getParameters().stream().map(VariableElement::getSimpleName).collect(Collectors.joining(", "))
                             + ");");
                       } else {
-                          pw.println("        return delegateProvider.getDelegate(true, " + field + ")." + ee.getSimpleName() + "("
+                          pw.println("        return delegateProvider.getDelegate(true, "
+                            + Stream.concat(Stream.of(field), ee.getParameters().stream().map(VariableElement::getSimpleName)).collect(Collectors.joining(", "))
+                            + ")." + ee.getSimpleName() + "("
                             + ee.getParameters().stream().map(VariableElement::getSimpleName).collect(Collectors.joining(", "))
                             + ");");
                       }
@@ -408,6 +654,8 @@ public class GenerateEntityImplementationsProcessor extends AbstractGenerateEnti
                   });
 
                 pw.println("}");
+
+                autogenerated.add("        DELEGATE_CREATORS.put(" + className + ".class, (DelegateCreator<" + className + ">) " + mapClassName + "::new);");
             }
         }
     }
@@ -457,7 +705,7 @@ public class GenerateEntityImplementationsProcessor extends AbstractGenerateEnti
                 pw.println("        return target;");
                 pw.println("    }");
 
-                cloners.add("        CLONERS_WITH_ID.put(" + className + ".class, (Cloner<" + className + ">) " + clonerImplClassName + "::deepClone);");
+                autogenerated.add("        CLONERS_WITH_ID.put(" + className + ".class, (Cloner<" + className + ">) " + clonerImplClassName + "::deepClone);");
 
                 if (methodsPerAttribute.containsKey("Id")) {
                     pw.println("    public static " + className + " deepCloneNoId(" + className + " original, " + className + " target) {");
@@ -476,7 +724,7 @@ public class GenerateEntityImplementationsProcessor extends AbstractGenerateEnti
                     pw.println("        return target;");
                     pw.println("    }");
 
-                    cloners.add("        CLONERS_WITHOUT_ID.put(" + className + ".class, (Cloner<" + className + ">) " + clonerImplClassName + "::deepCloneNoId);");
+                    autogenerated.add("        CLONERS_WITHOUT_ID.put(" + className + ".class, (Cloner<" + className + ">) " + clonerImplClassName + "::deepCloneNoId);");
                 }
                 pw.println("}");
             }

model/build-processor/src/main/java/org/keycloak/models/map/processor/Util.java

@@ -24,10 +24,14 @@ import java.util.LinkedHashSet;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
 import java.util.Set;
 import java.util.TreeSet;
 import java.util.stream.Collectors;
 import javax.lang.model.element.Element;
+import javax.lang.model.element.ExecutableElement;
+import javax.lang.model.element.Modifier;
 import javax.lang.model.element.Name;
 import javax.lang.model.element.TypeElement;
 import javax.lang.model.element.VariableElement;
@@ -86,4 +90,13 @@ public class Util {
         return true;
     }
 
+    protected static Optional<ExecutableElement> findParentMethodImplementation(List<? extends Element> allParentMembers, ExecutableElement method) {
+        return allParentMembers.stream()
+          .filter(ExecutableElement.class::isInstance)
+          .map(ExecutableElement.class::cast)
+          .filter(ee -> Objects.equals(ee.toString(), method.toString()))
+          .filter((ExecutableElement ee) ->  ! ee.getModifiers().contains(Modifier.ABSTRACT))
+          .findAny();
+    }
+
 }

model/map/src/main/java/org/keycloak/models/map/common/DeepCloner.java

@@ -1,13 +1,13 @@
 /*
  * Copyright 2021 Red Hat, Inc. and/or its affiliates
  * and other contributors as indicated by the @author tags.
- * 
+ *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  * http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -16,6 +16,8 @@
  */
 package org.keycloak.models.map.common;
 
+import org.keycloak.models.map.common.delegate.DelegateProvider;
+import org.keycloak.models.map.common.delegate.EntityFieldDelegate;
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -79,6 +81,30 @@ public class DeepCloner {
         V clone(V original, V target);
     }
 
+    /**
+     * Function that instantiates a delegation object of type {@code V} with the given delegate provider
+     * @param <V> Object class
+     */
+    @FunctionalInterface
+    public interface DelegateCreator<V> {
+        /**
+         * Function that instantiates a delegation object of type {@code V} with the given delegate provider.
+         */
+        V create(DelegateProvider<V> delegateProvider);
+    }
+
+    /**
+     * Function that instantiates a delegation object of type {@code V} with the given per-field delegate provider
+     * @param <V> Object class
+     */
+    @FunctionalInterface
+    public interface EntityFieldDelegateCreator<V> {
+        /**
+         * Function that instantiates a delegation object of type {@code V} with the given per-field delegate provider.
+         */
+        V create(EntityFieldDelegate<V> entityDelegateProvider);
+    }
+
     public static final DeepCloner DUMB_CLONER = new Builder().build();
 
     /**
@@ -87,8 +113,10 @@ public class DeepCloner {
     public static class Builder {
         private final Map<Class<?>, Supplier<?>> parameterlessConstructors = new HashMap<>();
         private final Map<Class<?>, Function<DeepCloner, ?>> constructors = new HashMap<>();
-        private final Map<Class<?>, Cloner> clonersWithId = new HashMap<>(org.keycloak.models.map.common.AutogeneratedCloners.CLONERS_WITH_ID);
+        private final Map<Class<?>, Cloner<?>> clonersWithId = new HashMap<>(org.keycloak.models.map.common.AutogeneratedCloners.CLONERS_WITH_ID);
-        private final Map<Class<?>, Cloner> clonersWithoutId = new HashMap<>(org.keycloak.models.map.common.AutogeneratedCloners.CLONERS_WITHOUT_ID);
+        private final Map<Class<?>, Cloner<?>> clonersWithoutId = new HashMap<>(org.keycloak.models.map.common.AutogeneratedCloners.CLONERS_WITHOUT_ID);
+        private final Map<Class<?>, DelegateCreator<?>> delegateCreators = new HashMap<>(org.keycloak.models.map.common.AutogeneratedCloners.DELEGATE_CREATORS);
+        private final Map<Class<?>, EntityFieldDelegateCreator<?>> entityFieldDelegateCreators = new HashMap<>(org.keycloak.models.map.common.AutogeneratedCloners.ENTITY_FIELD_DELEGATE_CREATORS);
         private Cloner<?> genericCloner = (from, to) -> { throw new IllegalStateException("Cloner not found for class " + (from == null ? "<null>" : from.getClass())); };
 
         /**
@@ -96,7 +124,7 @@ public class DeepCloner {
          * @return
          */
         public DeepCloner build() {
-            return new DeepCloner(parameterlessConstructors, constructors, clonersWithId, clonersWithoutId, genericCloner);
+            return new DeepCloner(parameterlessConstructors, constructors, delegateCreators, entityFieldDelegateCreators, clonersWithId, clonersWithoutId, genericCloner);
         }
 
         private <V> void forThisClassAndAllMarkedParentsAndInterfaces(Class<V> rootClazz, Consumer<Class<?>> action) {
@@ -123,7 +151,7 @@ public class DeepCloner {
 
         /**
          * Adds a method, often a constructor, that instantiates a record of type {@code V}.
-         * 
+         *
          * @param <V> Class or interface that would be instantiated by the given methods
          * @param clazz Class or interface that would be instantiated by the given methods
          * @param constructorNoParameters Parameterless function that creates a new instance of class {@code V}.
@@ -153,6 +181,38 @@ public class DeepCloner {
             return this;
         }
 
+        /**
+         * Adds a method that instantiates an per-field delegate of type {@code V}.
+         *
+         * @param <V> Class or interface that would be instantiated by the given methods
+         * @param clazz Class or interface that would be instantiated by the given methods
+         * @param constructor Function that creates a new instance of class {@code V}.
+         *          If {@code null}, such a single-parameter constructor is not available.
+         * @return This builder.
+         */
+        public <V> Builder delegateCreator(Class<V> clazz, EntityFieldDelegateCreator<V> delegateCreator) {
+            if (delegateCreator != null) {
+                forThisClassAndAllMarkedParentsAndInterfaces(clazz, cl -> this.entityFieldDelegateCreators.put(cl, delegateCreator));
+            }
+            return this;
+        }
+
+        /**
+         * Adds a method, often a constructor, that instantiates a delegate of type {@code V}.
+         *
+         * @param <V> Class or interface that would be instantiated by the given methods
+         * @param clazz Class or interface that would be instantiated by the given methods
+         * @param constructor Function that creates a new instance of class {@code V}.
+         *          If {@code null}, such a single-parameter constructor is not available.
+         * @return This builder.
+         */
+        public <V> Builder delegateCreator(Class<V> clazz, DelegateCreator<V> delegateCreator) {
+            if (delegateCreator != null) {
+                forThisClassAndAllMarkedParentsAndInterfaces(clazz, cl -> this.delegateCreators.put(cl, delegateCreator));
+            }
+            return this;
+        }
+
         /**
          * Adds a method that copies (as in a deep copy) an object properties from one object to another
          *
@@ -163,7 +223,7 @@ public class DeepCloner {
          *          function usually returns {@code to}
          * @return This builder.
          */
-        public <V> Builder cloner(Class<? extends V> clazz, Cloner cloner) {
+        public <V> Builder cloner(Class<? extends V> clazz, Cloner<?> cloner) {
             if (cloner != null) {
                 forThisClassAndAllMarkedParentsAndInterfaces(clazz, cl -> this.clonersWithId.put(cl, cloner));
             }
@@ -180,7 +240,7 @@ public class DeepCloner {
          *          function usually returns {@code to}
          * @return This builder.
          */
-        public <V> Builder cloner(Class<? extends V> clazz, Cloner clonerWithId, Cloner clonerWithoutId) {
+        public <V> Builder cloner(Class<? extends V> clazz, Cloner<?> clonerWithId, Cloner<?> clonerWithoutId) {
             if (clonerWithId != null) {
                 forThisClassAndAllMarkedParentsAndInterfaces(clazz, cl -> this.clonersWithId.put(cl, clonerWithId));
             }
@@ -193,7 +253,7 @@ public class DeepCloner {
         /**
          * Adds a method that copies (as in a deep copy) an object properties to another object for any class
          * that is not covered by a specific cloner set via {@link #cloner(Class, BiFunction)} method.
-         * 
+         *
          * @param <V> Class or interface whose instance would be copied over to another instance by the given cloner
          * @param genericCloner A method for cloning which copies properties of an object onto another object. This
          *          function usually returns {@code to}
@@ -209,20 +269,27 @@ public class DeepCloner {
 
     private final Map<Class<?>, Supplier<?>> parameterlessConstructors;
     private final Map<Class<?>, Function<DeepCloner, ?>> constructors;
-    private final Map<Class<?>, Cloner> clonersWithId;
+    private final Map<Class<?>, Cloner<?>> clonersWithId;
-    private final Map<Class<?>, Cloner> clonersWithoutId;
+    private final Map<Class<?>, Cloner<?>> clonersWithoutId;
+    private final Map<Class<?>, DelegateCreator<?>> delegateCreators;
+    private final Map<Class<?>, EntityFieldDelegateCreator<?>> entityFieldDelegateCreators;
     private final Cloner<?> genericCloner;
+    private final Map<Class<?>, Object> emptyInstances = new HashMap<>(AutogeneratedCloners.EMPTY_INSTANCES);
 
     private DeepCloner(Map<Class<?>, Supplier<?>> parameterlessConstructors,
       Map<Class<?>, Function<DeepCloner, ?>> constructors,
-      Map<Class<?>, Cloner> clonersWithId,
+      Map<Class<?>, DelegateCreator<?>> delegateCreators,
-      Map<Class<?>, Cloner> clonersWithoutId,
+      Map<Class<?>, EntityFieldDelegateCreator<?>> entityFieldDelegateCreators,
+      Map<Class<?>, Cloner<?>> clonersWithId,
+      Map<Class<?>, Cloner<?>> clonersWithoutId,
       Cloner<?> genericCloner) {
         this.parameterlessConstructors = parameterlessConstructors;
         this.constructors = constructors;
         this.clonersWithId = clonersWithId;
         this.clonersWithoutId = clonersWithoutId;
+        this.delegateCreators = delegateCreators;
         this.genericCloner = genericCloner;
+        this.entityFieldDelegateCreators = entityFieldDelegateCreators;
     }
 
     private <V> V getFromClassRespectingHierarchy(Map<Class<?>, V> map, Class<?> clazz) {
@@ -257,6 +324,43 @@ public class DeepCloner {
         return null;
     }
 
+    @SuppressWarnings("unchecked")
+    public <D, V extends D> D delegate(V delegate, DelegateProvider<D> delegateProvider) {
+        return delegate((Class<V>) delegate.getClass(), delegateProvider);
+    }
+
+    public <D, V extends D> D delegate(Class<V> delegateClass, DelegateProvider<D> delegateProvider) {
+        @SuppressWarnings("unchecked")
+        DelegateCreator<D> delegateCreator = (DelegateCreator<D>) getFromClassRespectingHierarchy(delegateCreators, delegateClass);
+        if (delegateCreator != null) {
+            return delegateCreator.create(delegateProvider);
+        }
+        throw new IllegalStateException("Cannot create delegate for " + delegateClass);
+    }
+
+    @SuppressWarnings("unchecked")
+    public <V> V entityFieldDelegate(V delegate, EntityFieldDelegate<V> delegateProvider) {
+        return entityFieldDelegate((Class<V>) delegate.getClass(), delegateProvider);
+    }
+
+    public <V> V entityFieldDelegate(Class<V> delegateClass, EntityFieldDelegate<V> delegateProvider) {
+        @SuppressWarnings("unchecked")
+        EntityFieldDelegateCreator<V> delegateCreator = (EntityFieldDelegateCreator<V>) getFromClassRespectingHierarchy(entityFieldDelegateCreators, delegateClass);
+        if (delegateCreator != null) {
+            return delegateCreator.create(delegateProvider);
+        }
+        throw new IllegalStateException("Cannot create delegate for " + delegateClass);
+    }
+
+    public <V> V emptyInstance(Class<V> instanceClass) {
+        @SuppressWarnings("unchecked")
+        V emptyInstance = (V) getFromClassRespectingHierarchy(emptyInstances, instanceClass);
+        if (emptyInstance != null) {
+            return emptyInstance;
+        }
+        throw new IllegalStateException("Cannot create empty instance for " + instanceClass);
+    }
+
     /**
      * Creates a new instance of the given class or interface if the parameterless constructor for that type is known.
      * @param <V> Type (class or a {@code @Root} interface) to create a new instance
@@ -301,6 +405,7 @@ public class DeepCloner {
      * @param clazz Type (class or a {@code @Root} interface) to create a new instance
      * @return See description
      */
+    @SuppressWarnings("unchecked")
     public <V> Class<? extends V> newInstanceType(Class<V> valueType) {
         if (valueType == null) {
             return null;
@@ -338,7 +443,7 @@ public class DeepCloner {
     }
 
     @SuppressWarnings("unchecked")
-    private <V> V deepClone(V from, V to, Map<Class<?>, Cloner> cloners) {
+    private <V> V deepClone(V from, V to, Map<Class<?>, Cloner<?>> cloners) {
         Cloner<V> cloner = (Cloner<V>) getFromClassRespectingHierarchy(cloners, from.getClass());
         if (cloner != null) {
             return cloner.clone(from, to);
@@ -383,6 +488,7 @@ public class DeepCloner {
      * @param from Original instance
      * @return Newly created instance or {@code null} if {@code from} is {@code null}.
      */
+    @SuppressWarnings("unchecked")
     public <V> V from(V from) {
         return from == null ? null : deepClone(from, newInstance((Class<V>) from.getClass()));
     }

model/map/src/main/java/org/keycloak/models/map/common/EntityField.java

@@ -0,0 +1,127 @@
+package org.keycloak.models.map.common;
+
+import java.util.Collection;
+import java.util.Map;
+
+/**
+ * Represents a field in an entity with appropriate accessors.
+ * 
+ * @author hmlnarik
+ * @param <E>
+ */
+public interface EntityField<E> {
+
+    /**
+     * Returns name of this field with no spaces where each word starts with a capital letter.
+     * @return
+     */
+    String getName();
+    /**
+     * Returns name of this field in lowercase with words separated by a dash ({@code -}).
+     * @return
+     */
+    String getNameDashed();
+    /**
+     * Returns the value of this field.
+     *
+     * @param e Entity
+     * @return Value of the field
+     */
+    Object get(E e);
+
+    /**
+     * Sets the value of this field. Does nothing by default. If you want to have a field set, override this method.
+     * @param <T>
+     * @param e Entity
+     * @param value Value of the field
+     */
+    default <T> void set(E e, T value) {};
+
+    /**
+     * Adds an element to the collection stored in this field.
+     * @param e Entity
+     * @param value Value to be added to the collection
+     * @throws ClassCastException If this field is not a collection.
+     */
+    default <T> void collectionAdd(E e, T value) {
+        @SuppressWarnings("unchecked")
+        Collection<T> c = (Collection<T>) get(e);
+        if (c != null) {
+            c.add(value);
+        }
+    }
+    /**
+     * Removes an element from the collection stored in this field.
+     * @param e Entity
+     * @param value Value to be added to the collection
+     * @return Defined by the underlying field. Preferrably it should return deleted object, but it can return
+     *    {@code true / false} indication of removal, or just {@code null}.
+     * @throws ClassCastException If this field is not a collection.
+     */
+    default <T> Object collectionRemove(E e, T value) {
+        Collection<?> c = (Collection<?>) get(e);
+        return c == null ? null : c.remove(value);
+    }
+
+    /**
+     * Retrieves a value from the map stored in this field.
+     * @param e Entity
+     * @param key Requested key
+     * @return Object mapped to this key
+     * @throws ClassCastException If this field is not a map.
+     */
+    default <K> Object mapGet(E e, K key) {
+        @SuppressWarnings("unchecked")
+        Map<K, ?> m = (Map<K, ?>) get(e);
+        return m == null ? null : m.get(key);
+    }
+    /**
+     * Adds a mapping to the map stored in this field.
+     * @param e Entity
+     * @param key Key to map
+     * @param value Mapped value
+     * @throws ClassCastException If this field is not a map.
+     */
+    default <K, T> void mapPut(E e, K key, T value) {
+        @SuppressWarnings("unchecked")
+        Map<K, T> m = (Map<K, T>) get(e);
+        if (m != null) {
+            m.put(key, value);
+        }
+    }
+    /**
+     * Removes a mapping from the map stored in this field.
+     * @param e Entity
+     * @param key Key to remove
+     * @return Object mapped to this key
+     * @throws ClassCastException If this field is not a map.
+     */
+    default <K> Object mapRemove(E e, K key) {
+        @SuppressWarnings("unchecked")
+        Map<K, ?> m = (Map<K, ?>) get(e);
+        if (m != null) {
+            return m.remove(key);
+        }
+        return null;
+    }
+
+    /**
+     * @return Returns the most specific type of this field.
+     */
+    default Class<?> getFieldClass() { return Object.class; }
+
+    /**
+     * @return If this field is a collection, returns type of its elements; otherwise returns {@code Void} class.
+     */
+    default Class<?> getCollectionElementClass() { return Void.class; }
+
+    /**
+     * @return If this field is a map, returns type of its keys; otherwise returns {@code Void} class.
+     */
+    default Class<?> getMapKeyClass() { return Void.class; }
+
+    /**
+     * @return If this field is a map, returns type of its values; otherwise returns {@code Void} class.
+     */
+    default Class<?> getMapValueClass() { return Void.class; }
+}

model/map/src/main/java/org/keycloak/models/map/common/delegate/DelegateProvider.java

@@ -17,7 +17,8 @@
 package org.keycloak.models.map.common.delegate;
 
 /**
- *
+ * Interface for a provider of a delegate of type {@code T}, optionally
+ * providing the flag on the object been updated.
  * @author hmlnarik
  */
 public interface DelegateProvider<T> {
@@ -27,7 +28,7 @@ public interface DelegateProvider<T> {
      * @param field Identification of the field this delegates operates on.
      * @return
      */
-    T getDelegate(boolean isRead, Object field);
+    T getDelegate(boolean isRead, Object field, Object... parameters);
 
     default boolean isUpdated() { return false; }
 }

model/map/src/main/java/org/keycloak/models/map/common/delegate/EntityFieldDelegate.java

@@ -0,0 +1,56 @@
+package org.keycloak.models.map.common.delegate;
+
+import java.util.Collection;
+import java.util.Map;
+
+import org.keycloak.models.map.common.EntityField;
+import org.keycloak.models.map.common.UpdatableEntity;
+
+public interface EntityFieldDelegate<E> extends UpdatableEntity {
+    // Non-collection values
+    Object get(EntityField<E> field);
+    default <T> void set(EntityField<E> field, T value) {}
+
+    default <T> void collectionAdd(EntityField<E> field, T value) {
+        @SuppressWarnings("unchecked")
+        Collection<T> c = (Collection<T>) get(field);
+        if (c != null) {
+            c.add(value);
+        }
+    }
+    default <T> Object collectionRemove(EntityField<E> field, T value) {
+        Collection<?> c = (Collection<?>) get(field);
+        return c == null ? null : c.remove(value);
+    }
+
+    /**
+     * 
+     * @param <K> Key type
+     * @param <T> Value type
+     * @param field Field identifier. Should be one of the generated {@code *Fields} enum constants.
+     * @param key Key
+     * @param valueClass class of the value
+     * @return
+     */
+    default <K> Object mapGet(EntityField<E> field, K key) {
+        @SuppressWarnings("unchecked")
+        Map<K, ?> m = (Map<K, ?>) get(field);
+        return m == null ? null : m.get(key);
+    }
+    default <K, T> void mapPut(EntityField<E> field, K key, T value) {
+        @SuppressWarnings("unchecked")
+        Map<K, T> m = (Map<K, T>) get(field);
+        if (m != null) {
+            m.put(key, value);
+        }
+    }
+    default <K> Object mapRemove(EntityField<E> field, K key) {
+        @SuppressWarnings("unchecked")
+        Map<K, ?> m = (Map<K, ?>) get(field);
+        if (m != null) {
+            return m.remove(key);
+        }
+        return null;
+    }
+
+}

model/map/src/main/java/org/keycloak/models/map/common/delegate/HasEntityFieldDelegate.java

@@ -0,0 +1,5 @@
+package org.keycloak.models.map.common.delegate;
+
+public interface HasEntityFieldDelegate<E> {
+    EntityFieldDelegate<E> getEntityFieldDelegate();
+}

model/map/src/main/java/org/keycloak/models/map/common/delegate/LazyDelegateProvider.java

@@ -35,7 +35,7 @@ public class LazyDelegateProvider<T extends UpdatableEntity> implements Delegate
     }
 
     @Override
-    public T getDelegate(boolean isRead, Object field) {
+    public T getDelegate(boolean isRead, Object field, Object... parameters) {
         if (! isDelegateInitialized()) {
             delegate.compareAndSet(null, delegateSupplier == null ? null : delegateSupplier.get(), false, true);
         }

model/map/src/main/java/org/keycloak/models/map/common/delegate/SimpleDelegateProvider.java

@@ -31,7 +31,7 @@ public class SimpleDelegateProvider<T extends UpdatableEntity> implements Delega
     }
 
     @Override
-    public T getDelegate(boolean isRead, Object field) {
+    public T getDelegate(boolean isRead, Object field, Object... parameters) {
         return this.delegate;
     }
 

model/map/src/main/java/org/keycloak/models/map/storage/tree/EmptyMapStorage.java

@@ -0,0 +1,100 @@
+/*
+ * Copyright 2021 Red Hat, Inc. and/or its affiliates
+ * and other contributors as indicated by the @author tags.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.keycloak.models.map.storage.tree;
+
+import org.keycloak.models.KeycloakSession;
+import org.keycloak.models.map.common.AbstractEntity;
+import org.keycloak.models.map.storage.MapKeycloakTransaction;
+import org.keycloak.models.map.storage.MapStorage;
+import org.keycloak.models.map.storage.QueryParameters;
+import java.util.stream.Stream;
+
+/**
+ *
+ * @author hmlnarik
+ */
+public class EmptyMapStorage<V extends AbstractEntity, M> implements MapStorage<V, M> {
+
+    private static final EmptyMapStorage<?, ?> INSTANCE = new EmptyMapStorage<>();
+
+    @SuppressWarnings("unchecked")
+    public static <V extends AbstractEntity, M> EmptyMapStorage<V, M> getInstance() {
+        return (EmptyMapStorage<V, M>) INSTANCE;
+    }
+
+    @Override
+    public MapKeycloakTransaction<V, M> createTransaction(KeycloakSession session) {
+        return new MapKeycloakTransaction<V, M>() {
+            @Override
+            public V create(V value) {
+                return null;
+            }
+
+            @Override
+            public V read(String key) {
+                return null;
+            }
+
+            @Override
+            public Stream<V> read(QueryParameters<M> queryParameters) {
+                return Stream.empty();
+            }
+
+            @Override
+            public long getCount(QueryParameters<M> queryParameters) {
+                return 0;
+            }
+
+            @Override
+            public boolean delete(String key) {
+                return false;
+            }
+
+            @Override
+            public long delete(QueryParameters<M> queryParameters) {
+                return 0;
+            }
+
+            @Override
+            public void begin() {
+            }
+
+            @Override
+            public void commit() {
+            }
+
+            @Override
+            public void rollback() {
+            }
+
+            @Override
+            public void setRollbackOnly() {
+            }
+
+            @Override
+            public boolean getRollbackOnly() {
+                return false;
+            }
+
+            @Override
+            public boolean isActive() {
+                return true;
+            }
+        };
+    }
+
+}

model/map/src/test/java/org/keycloak/models/map/client/MapClientEntityClonerTest.java

@@ -29,6 +29,7 @@ import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.not;
 import static org.hamcrest.Matchers.nullValue;
 import static org.hamcrest.Matchers.sameInstance;
+import static org.keycloak.models.map.common.DeepCloner.DUMB_CLONER;
 
 /**
  *
@@ -112,4 +113,40 @@ public class MapClientEntityClonerTest {
         assertThat(clonedInstance.getAuthenticationFlowBindingOverrides(), nullValue());
         assertThat(clonedInstance.getRegistrationToken(), nullValue());
     }
+
+    @Test
+    public void testCloneToExistingInstanceDumb() {
+        MapClientEntity newInstance = new MapClientEntityImpl();
+        newInstance.setId("my-id");
+        newInstance.setClientId("a-client-id");
+        newInstance.setAttribute("attr", Arrays.asList("aa", "bb", "cc"));
+        MapProtocolMapperEntity pmm = new MapProtocolMapperEntityImpl();
+        pmm.setId("pmm-id");
+        pmm.setConfig(new HashMap<>());
+        pmm.getConfig().put("key1", "value1");
+        pmm.getConfig().put("key2", "value2");
+        newInstance.setProtocolMapper("pmm-id", pmm);
+        newInstance.setAttribute("attr", Arrays.asList("aa", "bb", "cc"));
+
+        MapClientEntity clonedInstance = CLONER.newInstance(MapClientEntity.class);
+        assertThat(CLONER.deepCloneNoId(newInstance, clonedInstance), sameInstance(clonedInstance));
+        assertThat(clonedInstance, instanceOf(MapClientEntityImpl.class));
+        clonedInstance.setId("my-id2");
+        assertThat(clonedInstance.getId(), is("my-id2"));
+        assertThat(clonedInstance.getClientId(), is("a-client-id"));
+
+        assertThat(clonedInstance.getAttributes(), not(sameInstance(newInstance.getAttributes())));
+        assertThat(clonedInstance.getAttributes().keySet(), containsInAnyOrder("attr"));
+        assertThat(clonedInstance.getAttributes().get("attr"), contains("aa", "bb", "cc"));
+        assertThat(clonedInstance.getAttributes().get("attr"), not(sameInstance(newInstance.getAttributes().get("attr"))));
+
+        assertThat(clonedInstance.getProtocolMappers(), not(sameInstance(newInstance.getProtocolMappers())));
+        assertThat(clonedInstance.getProtocolMapper("pmm-id"), not(sameInstance(newInstance.getProtocolMapper("pmm-id"))));
+        assertThat(clonedInstance.getProtocolMapper("pmm-id"), equalTo(newInstance.getProtocolMapper("pmm-id")));
+        assertThat(clonedInstance.getProtocolMapper("pmm-id").getConfig(), not(sameInstance(newInstance.getProtocolMapper("pmm-id").getConfig())));
+        assertThat(clonedInstance.getProtocolMapper("pmm-id").getConfig(), equalTo(newInstance.getProtocolMapper("pmm-id").getConfig()));
+
+        assertThat(clonedInstance.getAuthenticationFlowBindingOverrides(), nullValue());
+        assertThat(clonedInstance.getRegistrationToken(), nullValue());
+    }
 }

testsuite/model/src/test/java/org/keycloak/testsuite/model/storage/tree/sample/Dict.java

@@ -0,0 +1,157 @@
+/*
+ * Copyright 2021 Red Hat, Inc. and/or its affiliates
+ * and other contributors as indicated by the @author tags.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.keycloak.testsuite.model.storage.tree.sample;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import org.keycloak.models.map.client.MapClientEntity;
+import org.keycloak.models.map.client.MapClientEntityFieldDelegate;
+import org.keycloak.models.map.client.MapClientEntityFields;
+import org.keycloak.models.map.common.DeepCloner;
+import org.keycloak.models.map.common.EntityField;
+import org.keycloak.models.map.common.UpdatableEntity;
+import org.keycloak.models.map.common.delegate.EntityFieldDelegate;
+import org.keycloak.models.map.common.delegate.HasEntityFieldDelegate;
+
+/**
+ *
+ * @author hmlnarik
+ */
+public class Dict<E> extends UpdatableEntity.Impl implements EntityFieldDelegate<E> {
+
+    public static final String CLIENT_FIELD_LOGO = "LOGO";
+    public static final String CLIENT_FIELD_ENABLED = "ENABLED";
+    public static final String CLIENT_FIELD_NAME = "NAME";
+
+    private static final Set<String> CLIENT_ALLOWED_KEYS = new HashSet<>(Arrays.asList(CLIENT_FIELD_NAME, CLIENT_FIELD_ENABLED, CLIENT_FIELD_LOGO));
+
+    public static MapClientEntity clientDelegate() {
+        // To be replaced by dynamic mapper config
+        Map<String, String> fieldName2key = new HashMap<>();
+        fieldName2key.put(MapClientEntityFields.ID.getName(), CLIENT_FIELD_NAME);
+        fieldName2key.put(MapClientEntityFields.CLIENT_ID.getName(), CLIENT_FIELD_NAME);
+        fieldName2key.put(MapClientEntityFields.ENABLED.getName(), CLIENT_FIELD_ENABLED);
+
+        Map<String, String> attributeName2key = new HashMap<>();
+        attributeName2key.put("logo", CLIENT_FIELD_LOGO);
+
+        Dict<MapClientEntity> dict = new Dict<>(CLIENT_ALLOWED_KEYS, fieldName2key, attributeName2key);
+        return DeepCloner.DUMB_CLONER.entityFieldDelegate(MapClientEntity.class, dict);
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <E> Dict<E> asDict(E entity) {
+        return (entity instanceof HasEntityFieldDelegate && ((HasEntityFieldDelegate<?>) entity).getEntityFieldDelegate() instanceof Dict)
+          ? (Dict<E>) ((HasEntityFieldDelegate<E>) entity).getEntityFieldDelegate()
+          : null;
+    }
+
+    private final Set<String> allowedKeys;
+    private final Map<String, Object> contents = new HashMap<>();
+    private final Map<String, String> fieldName2key;
+    private final Map<String, String> attributeName2key;
+
+    public Dict(Set<String> allowedKeys, Map<String, String> fieldName2key, Map<String, String> attributeName2key) {
+        this.allowedKeys = allowedKeys;
+        this.fieldName2key = fieldName2key;
+        this.attributeName2key = attributeName2key;
+    }
+
+    @Override
+    public Object get(EntityField<E> field) {
+        if ("Attributes".equals(field.getName())) {
+            return attributeName2key.entrySet().stream()
+              .filter(me -> get(me.getValue()) != null)
+              .collect(Collectors.toMap(me -> me.getKey(), me -> Collections.singletonList(get(me.getValue()))));
+        }
+        String key = fieldName2key.get(field.getName());
+        if (key != null) {
+            return get(key);
+        }
+        return null;
+    }
+
+    @Override
+    public <T> void set(EntityField<E> field, T value) {
+        String key = fieldName2key.get(field.getName());
+        if (key != null) {
+            put(key, value);
+        }
+    }
+
+    @Override
+    public <K> Object mapGet(EntityField<E> field, K key) {
+        if ("Attributes".equals(field.getName()) && attributeName2key.containsKey(key)) {
+            Object v = get(attributeName2key.get(key));
+            return v == null ? null : Collections.singletonList(get(attributeName2key.get(key)));
+        }
+        return null;
+    }
+
+    @Override
+    public <K, T> void mapPut(EntityField<E> field, K key, T value) {
+        if ("Attributes".equals(field.getName()) && attributeName2key.containsKey(key) && (value instanceof List)) {
+            List<?> l = (List<?>) value;
+            if (l.isEmpty()) {
+                remove(attributeName2key.get(key));
+            } else {
+                put(attributeName2key.get(key), l.get(0));
+            }
+        }
+    }
+
+    @Override
+    public <K> Object mapRemove(EntityField<E> field, K key) {
+        if ("Attributes".equals(field.getName()) && attributeName2key.containsKey(key)) {
+            Object o = remove(attributeName2key.get(key));
+            return o == null ? null : Collections.singletonList(o);
+        }
+        return null;
+    }
+
+    protected boolean isKeyAllowed(String key) {
+        return allowedKeys.contains(key);
+    }
+
+    public Object get(String key) {
+        return isKeyAllowed(key) ? contents.get(key) : null;
+    }
+
+    public void put(String key, Object value) {
+        if (isKeyAllowed(key)) {
+            updated |= ! Objects.equals(contents.put(key, value), value);
+        }
+    }
+
+    public Object remove(String key) {
+        key = key == null ? null : key.toUpperCase();
+        if (isKeyAllowed(key)) {
+            Object res = contents.remove(key);
+            updated |= res != null;
+            return res;
+        }
+        return null;
+    }
+}

testsuite/model/src/test/java/org/keycloak/testsuite/model/storage/tree/sample/DictStorage.java

@@ -0,0 +1,120 @@
+/*
+ * Copyright 2021 Red Hat, Inc. and/or its affiliates
+ * and other contributors as indicated by the @author tags.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.keycloak.testsuite.model.storage.tree.sample;
+
+import org.keycloak.models.KeycloakSession;
+import org.keycloak.models.map.common.AbstractEntity;
+import org.keycloak.models.map.common.DeepCloner;
+import org.keycloak.models.map.storage.MapKeycloakTransaction;
+import org.keycloak.models.map.storage.MapStorage;
+import org.keycloak.models.map.storage.QueryParameters;
+import java.util.List;
+import java.util.Objects;
+import java.util.stream.Stream;
+
+/**
+ *
+ * @author hmlnarik
+ */
+public class DictStorage<V extends AbstractEntity, M> implements MapStorage<V, M> {
+
+    private final DeepCloner cloner;
+
+    private final List<V> store;
+
+     public DictStorage(DeepCloner cloner, List<V> store) {
+        this.cloner = cloner;
+        this.store = store;
+    }
+
+    List<V> getStore() {
+        return store;
+    }
+
+    private final class Transaction implements MapKeycloakTransaction<V, M> {
+
+        @Override
+        public V create(V value) {
+            V res = cloner.from(value);
+            store.add(res);
+            return res;
+        }
+
+        @Override
+        public V read(String key) {
+            return store.stream()
+              .filter(e -> Objects.equals(e.getId(), key))
+              .findFirst()
+              .orElse(null);
+        }
+
+        @Override
+        public Stream<V> read(QueryParameters<M> queryParameters) {
+            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
+        }
+
+        @Override
+        public long getCount(QueryParameters<M> queryParameters) {
+            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
+        }
+
+        @Override
+        public boolean delete(String key) {
+            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
+        }
+
+        @Override
+        public long delete(QueryParameters<M> queryParameters) {
+            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
+        }
+
+        @Override
+        public void begin() {
+        }
+
+        @Override
+        public void commit() {
+        }
+
+        @Override
+        public void rollback() {
+            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
+        }
+
+        @Override
+        public void setRollbackOnly() {
+            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
+        }
+
+        @Override
+        public boolean getRollbackOnly() {
+            return false;
+        }
+
+        @Override
+        public boolean isActive() {
+            return true;
+        }
+
+    }
+
+    @Override
+    public MapKeycloakTransaction<V, M> createTransaction(KeycloakSession session) {
+        return new Transaction();
+    }
+
+}

testsuite/model/src/test/java/org/keycloak/testsuite/model/storage/tree/sample/DictTest.java

@@ -0,0 +1,60 @@
+package org.keycloak.testsuite.model.storage.tree.sample;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.empty;
+import static org.hamcrest.Matchers.hasItems;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.nullValue;
+
+import java.util.Arrays;
+
+import org.junit.Test;
+import org.keycloak.models.map.client.MapClientEntity;
+
+public class DictTest {
+    @Test
+    public void testDictClientFromMap() {
+        MapClientEntity mce = Dict.clientDelegate();
+        assertThat(mce.getClientId(), nullValue());
+        assertThat(mce.isEnabled(), nullValue());
+        assertThat(mce.getAttribute("logo"), nullValue());
+        assertThat(mce.getAttributes().keySet(), is(empty()));
+
+        Dict.asDict(mce).put(Dict.CLIENT_FIELD_NAME, "name");
+        Dict.asDict(mce).put(Dict.CLIENT_FIELD_ENABLED, false);
+        Dict.asDict(mce).put(Dict.CLIENT_FIELD_LOGO, "thisShouldBeBase64Logo");
+        Dict.asDict(mce).put("nonexistent", "nonexistent");
+
+        assertThat(mce.getId(), is("name"));
+        assertThat(mce.getClientId(), is("name"));
+        assertThat(mce.isEnabled(), is(false));
+        assertThat(mce.getAttribute("logo"), hasItems("thisShouldBeBase64Logo"));
+        assertThat(mce.getAttributes().keySet(), hasItems("logo"));
+    }
+
+    @Test
+    public void testDictClientFromEntity() {
+        MapClientEntity mce = Dict.clientDelegate();
+        
+        assertThat(Dict.asDict(mce).get(Dict.CLIENT_FIELD_NAME), nullValue());
+        assertThat(Dict.asDict(mce).get(Dict.CLIENT_FIELD_ENABLED), nullValue());
+        assertThat(Dict.asDict(mce).get(Dict.CLIENT_FIELD_LOGO), nullValue());
+
+        mce.setClientId("name");
+        mce.setEnabled(false);
+        mce.setAttribute("logo", Arrays.asList("thisShouldBeBase64Logo"));
+        mce.setAttribute("blah", Arrays.asList("thisShouldBeBase64Logofdas"));
+        
+        assertThat(mce.getAttributes().keySet(), hasItems("logo"));
+        
+        assertThat(Dict.asDict(mce).get(Dict.CLIENT_FIELD_NAME), is("name"));
+        assertThat(Dict.asDict(mce).get(Dict.CLIENT_FIELD_ENABLED), is(false));
+        assertThat(Dict.asDict(mce).get(Dict.CLIENT_FIELD_LOGO), is("thisShouldBeBase64Logo"));
+        
+        mce.setAttribute("logo", Arrays.asList("thisShouldBeAnotherBase64Logo"));
+        assertThat(Dict.asDict(mce).get(Dict.CLIENT_FIELD_LOGO), is("thisShouldBeAnotherBase64Logo"));
+
+        mce.removeAttribute("logo");
+        assertThat(Dict.asDict(mce).get(Dict.CLIENT_FIELD_LOGO), nullValue());
+    }
+}