diff --git a/processor/src/main/java/org/mapstruct/ap/model/MethodReference.java b/processor/src/main/java/org/mapstruct/ap/model/MethodReference.java
index 303f52e02..4b642376d 100644
--- a/processor/src/main/java/org/mapstruct/ap/model/MethodReference.java
+++ b/processor/src/main/java/org/mapstruct/ap/model/MethodReference.java
@@ -18,12 +18,12 @@
  */
 package org.mapstruct.ap.model;
 
-import org.mapstruct.ap.model.source.BuiltInMethod;
 import java.util.HashSet;
 import java.util.Set;
-import org.mapstruct.ap.model.common.ConversionContext;
 
+import org.mapstruct.ap.model.common.ConversionContext;
 import org.mapstruct.ap.model.common.Type;
+import org.mapstruct.ap.model.source.BuiltInMethod;
 import org.mapstruct.ap.model.source.SourceMethod;
 
 /**
@@ -34,19 +34,24 @@ import org.mapstruct.ap.model.source.SourceMethod;
 public class MethodReference extends MappingMethod {
 
     private final MapperReference declaringMapper;
+
+    /**
+     * In case this reference targets a built-in method, allows to pass specific context information to the invoked
+     * method. Currently this is only used to pass in the configured date format string when invoking a built-in method
+     * which requires that.
+     */
     private final String contextParam;
 
-
-    public MethodReference(SourceMethod method, MapperReference declaringMapper ) {
+    public MethodReference(SourceMethod method, MapperReference declaringMapper) {
         super( method );
         this.declaringMapper = declaringMapper;
-        this.contextParam =  null;
+        this.contextParam = null;
     }
 
-    public MethodReference(BuiltInMethod method, ConversionContext contextParam ) {
+    public MethodReference(BuiltInMethod method, ConversionContext contextParam) {
         super( method );
         this.declaringMapper = null;
-        this.contextParam =  method.getContextParameter( contextParam );
+        this.contextParam = method.getContextParameter( contextParam );
     }
 
     public MapperReference getDeclaringMapper() {
@@ -64,11 +69,4 @@ public class MethodReference extends MappingMethod {
     public String getContextParam() {
         return contextParam;
     }
-
-    private String quoteParamWhenNotNull(String param) {
-        if (param != null ) {
-            return param != null ? "\"" + param + "\"" : "null";
-        }
-        return null;
-    }
 }
diff --git a/processor/src/main/java/org/mapstruct/ap/model/common/ConversionContext.java b/processor/src/main/java/org/mapstruct/ap/model/common/ConversionContext.java
index 5d919fb4e..434873959 100644
--- a/processor/src/main/java/org/mapstruct/ap/model/common/ConversionContext.java
+++ b/processor/src/main/java/org/mapstruct/ap/model/common/ConversionContext.java
@@ -19,7 +19,7 @@
 package org.mapstruct.ap.model.common;
 
 /**
- * ConversionContext object passed to conversion providers.
+ * Context object passed to conversion providers and built-in methods.
  *
  * @author Gunnar Morling
  */
@@ -33,11 +33,11 @@ public interface ConversionContext {
     Type getTargetType();
 
     /**
-     * Returns the date format if this conversion is from String to
-     * {@link Date} or vice versa. Returns {@code null} for other types or
-     * if not given.
+     * Returns the date format if this conversion or built-in method is from String to a date type (e.g. {@link Date})
+     * or vice versa.
      *
-     * @return The date format if this conversion.
+     * @return The date format if this conversion or built-in method is from String to a date type. {@code null} is
+     *         returned for other types or if not given.
      */
     String getDateFormat();
 
diff --git a/processor/src/main/java/org/mapstruct/ap/model/source/BuiltInMethod.java b/processor/src/main/java/org/mapstruct/ap/model/source/BuiltInMethod.java
index 18c7ec2b1..e43feb52e 100644
--- a/processor/src/main/java/org/mapstruct/ap/model/source/BuiltInMethod.java
+++ b/processor/src/main/java/org/mapstruct/ap/model/source/BuiltInMethod.java
@@ -70,9 +70,9 @@ public abstract class BuiltInMethod extends ModelElement implements Method {
      * excluding generic type variables. When the implementor sees a need for this, this method can be overridden.
      */
     @Override
-    public boolean matches( Type sourceType, Type targetType ) {
+    public boolean matches(Type sourceType, Type targetType) {
         if ( targetType.erasure().isAssignableTo( getReturnType().erasure() )
-                && sourceType.erasure().isAssignableTo( getParameter().getType().erasure() ) ) {
+            && sourceType.erasure().isAssignableTo( getParameter().getType().erasure() ) ) {
             return doTypeVarsMatch( sourceType, targetType );
         }
         return false;
@@ -93,6 +93,7 @@ public abstract class BuiltInMethod extends ModelElement implements Method {
      *
      * declaring mapper is always null, being the MapperImpl itself. This method should not be overridden by
      * implementors
+     *
      * @return null
      */
     @Override
@@ -110,6 +111,7 @@ public abstract class BuiltInMethod extends ModelElement implements Method {
 
     /**
      * target parameter mechanism not supported for build-in-method
+     *
      * @return null
      */
     @Override
@@ -122,6 +124,7 @@ public abstract class BuiltInMethod extends ModelElement implements Method {
      * with context specific information such as a date format.
      *
      * @param conversionContext
+     *
      * @return null if no context parameter should be included
      *         "null" if there should be an explicit null call
      *         "'dateFormat'" for instance, to indicate how the build-in method should format the date
@@ -144,10 +147,11 @@ public abstract class BuiltInMethod extends ModelElement implements Method {
      * equals based on class
      *
      * @param obj other class
+     *
      * @return true when classes are the same
      */
     @Override
-    public boolean equals( Object obj ) {
+    public boolean equals(Object obj) {
         if ( obj == null ) {
             return false;
         }
@@ -160,9 +164,10 @@ public abstract class BuiltInMethod extends ModelElement implements Method {
      *
      * @param parameter source
      * @param returnType target
+     *
      * @return
      */
-    public boolean doTypeVarsMatch( Type parameter, Type returnType ) {
+    public boolean doTypeVarsMatch(Type parameter, Type returnType) {
         return true;
     }
 
diff --git a/processor/src/main/java/org/mapstruct/ap/processor/MapperCreationProcessor.java b/processor/src/main/java/org/mapstruct/ap/processor/MapperCreationProcessor.java
index 6e5060eb1..d041627d0 100644
--- a/processor/src/main/java/org/mapstruct/ap/processor/MapperCreationProcessor.java
+++ b/processor/src/main/java/org/mapstruct/ap/processor/MapperCreationProcessor.java
@@ -578,18 +578,20 @@ public class MapperCreationProcessor implements ModelElementProcessor<List<Sourc
             targetType = typeFactory.getReturnType( targetAcessor );
         }
 
-        // first try the SourceMethods
+        // first try the source methods
         String mappedElement = "property '" + Executables.getPropertyName( sourceAccessor ) + "'";
         MethodReference propertyMappingMethod = getMappingMethodReference(
-                getBestMatch( method, mappedElement, methods, sourceType, targetType ),
-                mapperReferences );
+            getBestMatch( method, mappedElement, methods, sourceType, targetType ),
+            mapperReferences
+        );
 
-        // then try BuiltInMethods
+        // then try built-in methods
         if ( propertyMappingMethod == null ) {
             propertyMappingMethod = getMappingMethodReference(
-                    getBestMatch( method, mappedElement, builtInMethods.getBuiltInMethods(), sourceType, targetType ),
-                    targetType,
-                    dateFormat );
+                getBestMatch( method, mappedElement, builtInMethods.getBuiltInMethods(), sourceType, targetType ),
+                targetType,
+                dateFormat
+            );
         }
 
         TypeConversion conversion = getConversion(
@@ -636,18 +638,22 @@ public class MapperCreationProcessor implements ModelElementProcessor<List<Sourc
             )
         );
 
-        // first try the SourceMethods
+        // first try the source methods
         MethodReference elementMappingMethod = getMappingMethodReference(
-                getBestMatch( method, "collection element", methods, sourceElementType, targetElementType ),
-                mapperReferences );
+            getBestMatch( method, "collection element", methods, sourceElementType, targetElementType ),
+            mapperReferences
+        );
 
-        // then try BuiltInMethods
+        // then try built-in methods
         if ( elementMappingMethod == null ) {
             elementMappingMethod = getMappingMethodReference(
-                    getBestMatch( method, "collection element", builtInMethods.getBuiltInMethods(), sourceElementType,
-                            targetElementType ),
-                    targetElementType,
-                    dateFormat );
+                getBestMatch(
+                    method, "collection element", builtInMethods.getBuiltInMethods(), sourceElementType,
+                    targetElementType
+                ),
+                targetElementType,
+                dateFormat
+            );
         }
 
         if ( !sourceElementType.isAssignableTo( targetElementType ) && conversion == null &&
@@ -693,29 +699,39 @@ public class MapperCreationProcessor implements ModelElementProcessor<List<Sourc
             "entry.getValue()"
         );
 
-        // first try the SourceMethods
+        // first try the source methods
         MethodReference keyMappingMethod = getMappingMethodReference(
-                getBestMatch( method, "map key", methods, sourceKeyType, targetKeyType ), mapperReferences );
+            getBestMatch( method, "map key", methods, sourceKeyType, targetKeyType ), mapperReferences
+        );
 
-        // then try BuiltInMethods
+        // then try built-in methods
         if ( keyMappingMethod == null ) {
             keyMappingMethod = getMappingMethodReference(
-                    getBestMatch( method, "map key", builtInMethods.getBuiltInMethods(), sourceKeyType, targetKeyType ),
-                    targetKeyType,
-                    keyDateFormat );
+                getBestMatch( method, "map key", builtInMethods.getBuiltInMethods(), sourceKeyType, targetKeyType ),
+                targetKeyType,
+                keyDateFormat
+            );
         }
 
-        // first try the SourceMethods
+        // first try the source methods
         MethodReference valueMappingMethod = getMappingMethodReference(
-                getBestMatch( method, "map value", methods, sourceValueType, targetValueType ),
-                mapperReferences );
+            getBestMatch( method, "map value", methods, sourceValueType, targetValueType ),
+            mapperReferences
+        );
 
-        // then try BuiltInMethods
+        // then try built-in methods
         if ( valueMappingMethod == null ) {
             valueMappingMethod = getMappingMethodReference(
-                    getBestMatch( method, "map value", builtInMethods.getBuiltInMethods(), sourceValueType, targetValueType ),
-                    targetValueType,
-                    valueDateFormat );
+                getBestMatch(
+                    method,
+                    "map value",
+                    builtInMethods.getBuiltInMethods(),
+                    sourceValueType,
+                    targetValueType
+                ),
+                targetValueType,
+                valueDateFormat
+            );
         }
 
         if ( !sourceKeyType.isAssignableTo( targetKeyType ) && keyConversion == null && keyMappingMethod == null ) {
@@ -764,10 +780,9 @@ public class MapperCreationProcessor implements ModelElementProcessor<List<Sourc
     }
 
 
-
     private <T extends Method> T getBestMatch(SourceMethod mappingMethod, String mappedElement,
-                                                      Iterable<T> methods, Type parameterType,
-                                                      Type returnType) {
+                                              Iterable<T> methods, Type parameterType,
+                                              Type returnType) {
         List<T> candidatesWithMathingTargetType = new ArrayList<T>();
 
         for ( T method : methods ) {
@@ -820,7 +835,8 @@ public class MapperCreationProcessor implements ModelElementProcessor<List<Sourc
 
 
     private <T extends Method> int addToCandidateListIfMinimal(List<T> candidatesWithBestMathingType,
-                                            int bestMatchingTypeDistance, T method, int currentTypeDistance) {
+                                                               int bestMatchingTypeDistance, T method,
+                                                               int currentTypeDistance) {
         if ( currentTypeDistance == bestMatchingTypeDistance ) {
             candidatesWithBestMathingType.add( method );
         }
@@ -833,7 +849,7 @@ public class MapperCreationProcessor implements ModelElementProcessor<List<Sourc
         return bestMatchingTypeDistance;
     }
 
-    private MethodReference getMappingMethodReference( SourceMethod method, List<MapperReference> mapperReferences ) {
+    private MethodReference getMappingMethodReference(SourceMethod method, List<MapperReference> mapperReferences) {
         if ( method != null ) {
             MapperReference mapperReference = null;
             for ( MapperReference ref : mapperReferences ) {
@@ -847,7 +863,7 @@ public class MapperCreationProcessor implements ModelElementProcessor<List<Sourc
         return null;
     }
 
-    private MethodReference getMappingMethodReference( BuiltInMethod method, Type returnType, String dateFormat ) {
+    private MethodReference getMappingMethodReference(BuiltInMethod method, Type returnType, String dateFormat) {
         if ( method != null ) {
             virtualMethods.add( new VirtualMappingMethod( method ) );
             ConversionContext ctx = new DefaultConversionContext( typeFactory, returnType, dateFormat );
@@ -980,7 +996,7 @@ public class MapperCreationProcessor implements ModelElementProcessor<List<Sourc
 
     /**
      * A getter could be an alternative getReturnType-accessor if a setter is not available, and the
- getReturnType is a collection.
+     * getReturnType is a collection.
      *
      * Provided such a getter is initialized lazy by the getReturnType class, e.g. in generated JAXB beans.
      *