diff --git a/server-spi/src/main/java/org/keycloak/component/ComponentFactory.java b/server-spi/src/main/java/org/keycloak/component/ComponentFactory.java
index b4c6f44610..32f70a87b4 100644
--- a/server-spi/src/main/java/org/keycloak/component/ComponentFactory.java
+++ b/server-spi/src/main/java/org/keycloak/component/ComponentFactory.java
@@ -98,7 +98,7 @@ public interface ComponentFactory<CreatedType, ProviderType extends Provider> ex
      */
     default
     List<ProviderConfigProperty> getCommonProviderConfigProperties() {
-        return Collections.EMPTY_LIST;
+        return Collections.emptyList();
     }
 
     /**
@@ -109,7 +109,7 @@ public interface ComponentFactory<CreatedType, ProviderType extends Provider> ex
      */
     default
     Map<String, Object> getTypeMetadata() {
-        return Collections.EMPTY_MAP;
+        return Collections.emptyMap();
 
     }
 
diff --git a/server-spi/src/main/java/org/keycloak/models/AuthenticatorConfigModel.java b/server-spi/src/main/java/org/keycloak/models/AuthenticatorConfigModel.java
index 8bcae9f65a..308613d990 100755
--- a/server-spi/src/main/java/org/keycloak/models/AuthenticatorConfigModel.java
+++ b/server-spi/src/main/java/org/keycloak/models/AuthenticatorConfigModel.java
@@ -29,7 +29,7 @@ public class AuthenticatorConfigModel implements Serializable {
 
     private String id;
     private String alias;
-    private Map<String, String> config = new HashMap<String, String>();
+    private Map<String, String> config = new HashMap<>();
 
 
     public String getId() {
diff --git a/server-spi/src/main/java/org/keycloak/models/IdentityProviderModel.java b/server-spi/src/main/java/org/keycloak/models/IdentityProviderModel.java
index 9aec8ffe5e..63b8a475ba 100755
--- a/server-spi/src/main/java/org/keycloak/models/IdentityProviderModel.java
+++ b/server-spi/src/main/java/org/keycloak/models/IdentityProviderModel.java
@@ -66,7 +66,7 @@ public class IdentityProviderModel implements Serializable {
      * <p>A map containing the configuration and properties for a specific identity provider instance and implementation. The items
      * in the map are understood by the identity provider implementation.</p>
      */
-    private Map<String, String> config = new HashMap<String, String>();
+    private Map<String, String> config = new HashMap<>();
 
     public IdentityProviderModel() {
     }
@@ -77,7 +77,7 @@ public class IdentityProviderModel implements Serializable {
             this.providerId = model.getProviderId();
             this.alias = model.getAlias();
             this.displayName = model.getDisplayName();
-            this.config = new HashMap<String, String>(model.getConfig());
+            this.config = new HashMap<>(model.getConfig());
             this.enabled = model.isEnabled();
             this.trustEmail = model.isTrustEmail();
             this.storeToken = model.isStoreToken();
diff --git a/server-spi/src/main/java/org/keycloak/models/RequiredCredentialModel.java b/server-spi/src/main/java/org/keycloak/models/RequiredCredentialModel.java
index d942412a92..85ad4552fb 100755
--- a/server-spi/src/main/java/org/keycloak/models/RequiredCredentialModel.java
+++ b/server-spi/src/main/java/org/keycloak/models/RequiredCredentialModel.java
@@ -79,7 +79,7 @@ public class RequiredCredentialModel implements Serializable {
     public static final RequiredCredentialModel KERBEROS;
 
     static {
-        Map<String, RequiredCredentialModel> map = new HashMap<String, RequiredCredentialModel>();
+        Map<String, RequiredCredentialModel> map = new HashMap<>();
         PASSWORD = new RequiredCredentialModel();
         PASSWORD.setType(PasswordCredentialModel.TYPE);
         PASSWORD.setInput(true);
diff --git a/server-spi/src/main/java/org/keycloak/models/utils/HmacOTP.java b/server-spi/src/main/java/org/keycloak/models/utils/HmacOTP.java
index e3a1bd2347..f8489d4cee 100755
--- a/server-spi/src/main/java/org/keycloak/models/utils/HmacOTP.java
+++ b/server-spi/src/main/java/org/keycloak/models/utils/HmacOTP.java
@@ -174,8 +174,7 @@ public class HmacOTP {
 
         // Copy all the REAL bytes, not the "first"
         byte[] ret = new byte[bArray.length - 1];
-        for (int i = 0; i < ret.length; i++)
-            ret[i] = bArray[i + 1];
+        System.arraycopy(bArray, 1, ret, 0, ret.length);
         return ret;
     }
 }
diff --git a/server-spi/src/main/java/org/keycloak/storage/UserStorageProviderFactory.java b/server-spi/src/main/java/org/keycloak/storage/UserStorageProviderFactory.java
index 4d31aeebac..1815c5a4dc 100755
--- a/server-spi/src/main/java/org/keycloak/storage/UserStorageProviderFactory.java
+++ b/server-spi/src/main/java/org/keycloak/storage/UserStorageProviderFactory.java
@@ -78,7 +78,7 @@ public interface UserStorageProviderFactory<T extends UserStorageProvider> exten
 
     @Override
     default List<ProviderConfigProperty> getConfigProperties() {
-        return Collections.EMPTY_LIST;
+        return Collections.emptyList();
     }
 
     @Override
diff --git a/server-spi/src/main/java/org/keycloak/storage/adapter/AbstractUserAdapter.java b/server-spi/src/main/java/org/keycloak/storage/adapter/AbstractUserAdapter.java
index b0d7ca3772..ae8eabe680 100644
--- a/server-spi/src/main/java/org/keycloak/storage/adapter/AbstractUserAdapter.java
+++ b/server-spi/src/main/java/org/keycloak/storage/adapter/AbstractUserAdapter.java
@@ -62,7 +62,7 @@ public abstract class AbstractUserAdapter implements UserModel {
 
     @Override
     public Set<String> getRequiredActions() {
-        return Collections.EMPTY_SET;
+        return Collections.emptySet();
     }
 
     @Override
@@ -94,7 +94,7 @@ public abstract class AbstractUserAdapter implements UserModel {
      * @return
      */
     protected Set<GroupModel> getGroupsInternal() {
-        return Collections.EMPTY_SET;
+        return Collections.emptySet();
     }
 
     /**
@@ -138,7 +138,7 @@ public abstract class AbstractUserAdapter implements UserModel {
     public Set<RoleModel> getRealmRoleMappings() {
         Set<RoleModel> roleMappings = getRoleMappings();
 
-        Set<RoleModel> realmRoles = new HashSet<RoleModel>();
+        Set<RoleModel> realmRoles = new HashSet<>();
         for (RoleModel role : roleMappings) {
             RoleContainerModel container = role.getContainer();
             if (container instanceof RealmModel) {
@@ -152,7 +152,7 @@ public abstract class AbstractUserAdapter implements UserModel {
     public Set<RoleModel> getClientRoleMappings(ClientModel app) {
         Set<RoleModel> roleMappings = getRoleMappings();
 
-        Set<RoleModel> roles = new HashSet<RoleModel>();
+        Set<RoleModel> roles = new HashSet<>();
         for (RoleModel role : roleMappings) {
             RoleContainerModel container = role.getContainer();
             if (container instanceof ClientModel) {
@@ -190,7 +190,7 @@ public abstract class AbstractUserAdapter implements UserModel {
     }
 
     protected Set<RoleModel> getRoleMappingsInternal() {
-        return Collections.EMPTY_SET;
+        return Collections.emptySet();
     }
 
     @Override
diff --git a/server-spi/src/main/java/org/keycloak/storage/adapter/AbstractUserAdapterFederatedStorage.java b/server-spi/src/main/java/org/keycloak/storage/adapter/AbstractUserAdapterFederatedStorage.java
index fe9a41ed1b..c14f981fc9 100644
--- a/server-spi/src/main/java/org/keycloak/storage/adapter/AbstractUserAdapterFederatedStorage.java
+++ b/server-spi/src/main/java/org/keycloak/storage/adapter/AbstractUserAdapterFederatedStorage.java
@@ -102,7 +102,7 @@ public abstract class AbstractUserAdapterFederatedStorage implements UserModel {
      * @return
      */
     protected Set<GroupModel> getGroupsInternal() {
-        return Collections.EMPTY_SET;
+        return Collections.emptySet();
     }
 
     /**
@@ -126,8 +126,7 @@ public abstract class AbstractUserAdapterFederatedStorage implements UserModel {
      */
     @Override
     public Set<GroupModel> getGroups() {
-        Set<GroupModel> set = new HashSet<>();
-        set.addAll(getFederatedStorage().getGroups(realm, this.getId()));
+        Set<GroupModel> set = new HashSet<>(getFederatedStorage().getGroups(realm, this.getId()));
         if (appendDefaultGroups()) set.addAll(realm.getDefaultGroups());
         set.addAll(getGroupsInternal());
         return set;
@@ -163,7 +162,7 @@ public abstract class AbstractUserAdapterFederatedStorage implements UserModel {
     public Set<RoleModel> getRealmRoleMappings() {
         Set<RoleModel> roleMappings = getRoleMappings();
 
-        Set<RoleModel> realmRoles = new HashSet<RoleModel>();
+        Set<RoleModel> realmRoles = new HashSet<>();
         for (RoleModel role : roleMappings) {
             RoleContainerModel container = role.getContainer();
             if (container instanceof RealmModel) {
@@ -185,7 +184,7 @@ public abstract class AbstractUserAdapterFederatedStorage implements UserModel {
     public Set<RoleModel> getClientRoleMappings(ClientModel app) {
         Set<RoleModel> roleMappings = getRoleMappings();
 
-        Set<RoleModel> roles = new HashSet<RoleModel>();
+        Set<RoleModel> roles = new HashSet<>();
         for (RoleModel role : roleMappings) {
             RoleContainerModel container = role.getContainer();
             if (container instanceof ClientModel) {
@@ -223,7 +222,7 @@ public abstract class AbstractUserAdapterFederatedStorage implements UserModel {
     }
 
     protected Set<RoleModel> getRoleMappingsInternal() {
-        return Collections.EMPTY_SET;
+        return Collections.emptySet();
     }
 
     /**
@@ -235,8 +234,7 @@ public abstract class AbstractUserAdapterFederatedStorage implements UserModel {
      */
     @Override
     public Set<RoleModel> getRoleMappings() {
-        Set<RoleModel> set = new HashSet<>();
-        set.addAll(getFederatedRoleMappings());
+        Set<RoleModel> set = new HashSet<>(getFederatedRoleMappings());
         if (appendDefaultRolesToRoleMappings()) set.addAll(DefaultRoles.getDefaultRoles(realm));
         set.addAll(getRoleMappingsInternal());
         return set;