diff --git a/saml-core/src/main/java/org/keycloak/saml/processing/core/util/IDFedLSInputResolver.java b/saml-core/src/main/java/org/keycloak/saml/processing/core/util/IDFedLSInputResolver.java
index c5c3c95ddf..299ddaa46a 100755
--- a/saml-core/src/main/java/org/keycloak/saml/processing/core/util/IDFedLSInputResolver.java
+++ b/saml-core/src/main/java/org/keycloak/saml/processing/core/util/IDFedLSInputResolver.java
@@ -21,6 +21,7 @@ import java.io.InputStream;
 import java.io.Reader;
 import java.net.URL;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.Map;
@@ -39,69 +40,71 @@ public class IDFedLSInputResolver implements LSResourceResolver {
 
     protected static final Logger logger = Logger.getLogger(IDFedLSInputResolver.class);
 
-    private static Map<String, String> schemaLocationMap = new LinkedHashMap<String, String>(); // thread safe for reading
+    private static final Map<String, String> schemaLocationMap;
 
     static {
+        Map<String, String> schemaLocations = new LinkedHashMap<>();
         // XML Schema/DTD
-        schemaLocationMap.put("datatypes.dtd", "schema/w3c/xmlschema/datatypes.dtd");
-        schemaLocationMap.put("XMLSchema.dtd", "schema/w3c/xmlschema/XMLSchema.dtd");
-        schemaLocationMap.put("http://www.w3.org/2001/XMLSchema.dtd", "schema/w3c/xmlschema/XMLSchema.dtd");        
-        schemaLocationMap.put("http://www.w3.org/2001/xml.xsd", "schema/w3c/xmlschema/xml.xsd");
+        schemaLocations.put("datatypes.dtd", "schema/w3c/xmlschema/datatypes.dtd");
+        schemaLocations.put("XMLSchema.dtd", "schema/w3c/xmlschema/XMLSchema.dtd");
+        schemaLocations.put("http://www.w3.org/2001/XMLSchema.dtd", "schema/w3c/xmlschema/XMLSchema.dtd");
+        schemaLocations.put("http://www.w3.org/2001/xml.xsd", "schema/w3c/xmlschema/xml.xsd");
 
         // XML DSIG
-        schemaLocationMap.put("http://www.w3.org/2000/09/xmldsig#", "schema/w3c/xmldsig/xmldsig-core-schema.xsd");
-        schemaLocationMap.put("http://www.w3.org/TR/2002/REC-xmldsig-core-20020212/xmldsig-core-schema.xsd",
+        schemaLocations.put("http://www.w3.org/2000/09/xmldsig#", "schema/w3c/xmldsig/xmldsig-core-schema.xsd");
+        schemaLocations.put("http://www.w3.org/TR/2002/REC-xmldsig-core-20020212/xmldsig-core-schema.xsd",
                 "schema/w3c/xmldsig/xmldsig-core-schema.xsd");
-        schemaLocationMap.put("http://www.w3.org/TR/xmldsig-core/xmldsig-core-schema.xsd", "schema/w3c/xmldsig/xmldsig-core-schema.xsd");
+        schemaLocations.put("http://www.w3.org/TR/xmldsig-core/xmldsig-core-schema.xsd", "schema/w3c/xmldsig/xmldsig-core-schema.xsd");
 
         // XML Enc
-        schemaLocationMap.put("http://www.w3.org/2001/04/xmlenc#", "schema/w3c/xmlenc/xenc-schema.xsd");
-        schemaLocationMap.put("http://www.w3.org/TR/2002/REC-xmlenc-core-20021210/xenc-schema.xsd",
+        schemaLocations.put("http://www.w3.org/2001/04/xmlenc#", "schema/w3c/xmlenc/xenc-schema.xsd");
+        schemaLocations.put("http://www.w3.org/TR/2002/REC-xmlenc-core-20021210/xenc-schema.xsd",
                 "schema/w3c/xmlenc/xenc-schema.xsd");
 
         // XACML
-        schemaLocationMap.put("access_control-xacml-2.0-context-schema-os.xsd",
+        schemaLocations.put("access_control-xacml-2.0-context-schema-os.xsd",
                 "schema/xacml/access_control-xacml-2.0-context-schema-os.xsd");
-        schemaLocationMap.put("http://docs.oasis-open.org/xacml/2.0/access_control-xacml-2.0-context-schema-os.xsd",
-                "schema/xacml/access_control-xacml-2.0-context-schema-os.xsd");        
-        schemaLocationMap.put("access_control-xacml-2.0-policy-schema-os.xsd",
+        schemaLocations.put("http://docs.oasis-open.org/xacml/2.0/access_control-xacml-2.0-context-schema-os.xsd",
+                "schema/xacml/access_control-xacml-2.0-context-schema-os.xsd");
+        schemaLocations.put("access_control-xacml-2.0-policy-schema-os.xsd",
                 "schema/xacml/access_control-xacml-2.0-policy-schema-os.xsd");
 
         // SAML
-        schemaLocationMap.put("saml-schema-assertion-2.0.xsd", "schema/saml/v2/saml-schema-assertion-2.0.xsd");
-        schemaLocationMap.put("http://www.oasis-open.org/committees/download.php/11027/sstc-saml-schema-assertion-2.0.xsd", "schema/saml/v2/saml-schema-assertion-2.0.xsd");
-        schemaLocationMap.put("saml-schema-protocol-2.0.xsd", "schema/saml/v2/saml-schema-protocol-2.0.xsd");
-        schemaLocationMap.put("http://www.oasis-open.org/committees/download.php/11026/sstc-saml-schema-protocol-2.0.xsd", "schema/saml/v2/saml-schema-protocol-2.0.xsd");
-        schemaLocationMap.put("saml-schema-metadata-2.0.xsd", "schema/saml/v2/saml-schema-metadata-2.0.xsd");
-        schemaLocationMap.put("saml-schema-x500-2.0.xsd", "schema/saml/v2/saml-schema-x500-2.0.xsd");
-        schemaLocationMap.put("saml-schema-xacml-2.0.xsd", "schema/saml/v2/saml-schema-xacml-2.0.xsd");
-        schemaLocationMap.put("saml-schema-xacml-2.0.xsd", "schema/saml/v2/saml-schema-xacml-2.0.xsd");
-        schemaLocationMap.put("saml-schema-authn-context-2.0.xsd", "schema/saml/v2/saml-schema-authn-context-2.0.xsd");
-        schemaLocationMap.put("saml-schema-authn-context-types-2.0.xsd",
+        schemaLocations.put("saml-schema-assertion-2.0.xsd", "schema/saml/v2/saml-schema-assertion-2.0.xsd");
+        schemaLocations.put("http://www.oasis-open.org/committees/download.php/11027/sstc-saml-schema-assertion-2.0.xsd", "schema/saml/v2/saml-schema-assertion-2.0.xsd");
+        schemaLocations.put("saml-schema-protocol-2.0.xsd", "schema/saml/v2/saml-schema-protocol-2.0.xsd");
+        schemaLocations.put("http://www.oasis-open.org/committees/download.php/11026/sstc-saml-schema-protocol-2.0.xsd", "schema/saml/v2/saml-schema-protocol-2.0.xsd");
+        schemaLocations.put("saml-schema-metadata-2.0.xsd", "schema/saml/v2/saml-schema-metadata-2.0.xsd");
+        schemaLocations.put("saml-schema-x500-2.0.xsd", "schema/saml/v2/saml-schema-x500-2.0.xsd");
+        schemaLocations.put("saml-schema-xacml-2.0.xsd", "schema/saml/v2/saml-schema-xacml-2.0.xsd");
+        schemaLocations.put("saml-schema-xacml-2.0.xsd", "schema/saml/v2/saml-schema-xacml-2.0.xsd");
+        schemaLocations.put("saml-schema-authn-context-2.0.xsd", "schema/saml/v2/saml-schema-authn-context-2.0.xsd");
+        schemaLocations.put("saml-schema-authn-context-types-2.0.xsd",
                 "schema/saml/v2/saml-schema-authn-context-types-2.0.xsd");
 
-        schemaLocationMap.put("saml-schema-assertion-1.0.xsd", "schema/saml/v1/saml-schema-assertion-1.0.xsd");
-        schemaLocationMap.put("oasis-sstc-saml-schema-assertion-1.1.xsd",
+        schemaLocations.put("saml-schema-assertion-1.0.xsd", "schema/saml/v1/saml-schema-assertion-1.0.xsd");
+        schemaLocations.put("oasis-sstc-saml-schema-assertion-1.1.xsd",
                 "schema/saml/v1/oasis-sstc-saml-schema-assertion-1.1.xsd");
-        schemaLocationMap.put("saml-schema-protocol-1.1.xsd", "schema/saml/v1/saml-schema-protocol-1.1.xsd");
+        schemaLocations.put("saml-schema-protocol-1.1.xsd", "schema/saml/v1/saml-schema-protocol-1.1.xsd");
 
-        schemaLocationMap.put("access_control-xacml-2.0-saml-assertion-schema-os.xsd",
+        schemaLocations.put("access_control-xacml-2.0-saml-assertion-schema-os.xsd",
                 "schema/saml/v2/access_control-xacml-2.0-saml-assertion-schema-os.xsd");
 
-        schemaLocationMap.put("access_control-xacml-2.0-saml-protocol-schema-os.xsd",
+        schemaLocations.put("access_control-xacml-2.0-saml-protocol-schema-os.xsd",
                 "schema/saml/v2/access_control-xacml-2.0-saml-protocol-schema-os.xsd");
-        
-        
+
+
         // WS-T
-        schemaLocationMap.put("http://docs.oasis-open.org/ws-sx/ws-trust/200512", "schema/wstrust/v1_3/ws-trust-1.3.xsd");
-        schemaLocationMap.put("http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd",
+        schemaLocations.put("http://docs.oasis-open.org/ws-sx/ws-trust/200512", "schema/wstrust/v1_3/ws-trust-1.3.xsd");
+        schemaLocations.put("http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd",
                 "schema/wstrust/v1_3/oasis-200401-wss-wssecurity-secext-1.0.xsd");
-        schemaLocationMap.put("http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd",
+        schemaLocations.put("http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd",
                 "schema/wstrust/v1_3/oasis-200401-wss-wssecurity-utility-1.0.xsd");
-        schemaLocationMap.put("http://schemas.xmlsoap.org/ws/2004/09/policy", "schema/wstrust/v1_3/ws-policy.xsd");
-        schemaLocationMap.put("http://schemas.xmlsoap.org/ws/2004/09/policy/ws-policy.xsd", "schema/wstrust/v1_3/ws-policy.xsd");
-        schemaLocationMap.put("http://www.w3.org/2005/08/addressing", "schema/wstrust/v1_3/ws-addr.xsd");
-        schemaLocationMap.put("http://www.w3.org/2006/03/addressing/ws-addr.xsd", "schema/wstrust/v1_3/ws-addr.xsd");
+        schemaLocations.put("http://schemas.xmlsoap.org/ws/2004/09/policy", "schema/wstrust/v1_3/ws-policy.xsd");
+        schemaLocations.put("http://schemas.xmlsoap.org/ws/2004/09/policy/ws-policy.xsd", "schema/wstrust/v1_3/ws-policy.xsd");
+        schemaLocations.put("http://www.w3.org/2005/08/addressing", "schema/wstrust/v1_3/ws-addr.xsd");
+        schemaLocations.put("http://www.w3.org/2006/03/addressing/ws-addr.xsd", "schema/wstrust/v1_3/ws-addr.xsd");
+        schemaLocationMap = Collections.unmodifiableMap(schemaLocations);
     }
 
     public static Collection<String> schemas() {
@@ -116,12 +119,12 @@ public class IDFedLSInputResolver implements LSResourceResolver {
         if (systemId == null) {
             throw new IllegalArgumentException("Expected systemId");
         }
-        
+
         final String loc = schemaLocationMap.get(systemId);
         if (loc == null) {
             return null;
         }
-        
+
         return new IDFedLSInput(baseURI, loc, publicId, systemId);
     }
 
@@ -210,7 +213,7 @@ public class IDFedLSInputResolver implements LSResourceResolver {
 
         @Override
         public String toString() {
-            return "PicketLinkLSInput [baseURI=" + baseURI + ", loc=" + loc + ", publicId=" + publicId + ", systemId="
+            return "IDFedLSInput [baseURI=" + baseURI + ", loc=" + loc + ", publicId=" + publicId + ", systemId="
                     + systemId + "]";
         }
     }