diff --git a/integrationtest/src/test/java/org/mapstruct/itest/tests/FullFeatureCompilationExclusionCliEnhancer.java b/integrationtest/src/test/java/org/mapstruct/itest/tests/FullFeatureCompilationExclusionCliEnhancer.java
index e64b20799..c0ea96fd5 100644
--- a/integrationtest/src/test/java/org/mapstruct/itest/tests/FullFeatureCompilationExclusionCliEnhancer.java
+++ b/integrationtest/src/test/java/org/mapstruct/itest/tests/FullFeatureCompilationExclusionCliEnhancer.java
@@ -44,7 +44,7 @@ public final class FullFeatureCompilationExclusionCliEnhancer implements Process
             default:
         }
 
-        Collection<String> result = new ArrayList<String>( additionalExcludes.size() );
+        Collection<String> result = new ArrayList<>(additionalExcludes.size());
         for ( int i = 0; i < additionalExcludes.size(); i++ ) {
             result.add( "-DadditionalExclude" + i + "=" + additionalExcludes.get( i ) );
         }
diff --git a/integrationtest/src/test/java/org/mapstruct/itest/tests/GradleIncrementalCompilationTest.java b/integrationtest/src/test/java/org/mapstruct/itest/tests/GradleIncrementalCompilationTest.java
index 016258246..3d496906c 100644
--- a/integrationtest/src/test/java/org/mapstruct/itest/tests/GradleIncrementalCompilationTest.java
+++ b/integrationtest/src/test/java/org/mapstruct/itest/tests/GradleIncrementalCompilationTest.java
@@ -62,7 +62,7 @@ public class GradleIncrementalCompilationTest {
     }
 
     private GradleRunner getRunner(String... additionalArguments) {
-        List<String> fullArguments = new ArrayList<String>( compileArgs );
+        List<String> fullArguments = new ArrayList<>(compileArgs);
         fullArguments.addAll( Arrays.asList( additionalArguments ) );
         return runner.withArguments( fullArguments );
     }
diff --git a/processor/src/main/java/org/mapstruct/ap/internal/conversion/BigDecimalToStringConversion.java b/processor/src/main/java/org/mapstruct/ap/internal/conversion/BigDecimalToStringConversion.java
index d696cf5bb..92a93e389 100644
--- a/processor/src/main/java/org/mapstruct/ap/internal/conversion/BigDecimalToStringConversion.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/conversion/BigDecimalToStringConversion.java
@@ -45,7 +45,7 @@ public class BigDecimalToStringConversion extends AbstractNumberToStringConversi
     public String getFromExpression(ConversionContext conversionContext) {
         if ( requiresDecimalFormat( conversionContext ) ) {
             StringBuilder sb = new StringBuilder();
-            sb.append( "(" + bigDecimal( conversionContext ) + ") " );
+            sb.append( "(" ).append( bigDecimal( conversionContext ) ).append( ") " );
             appendDecimalFormatter( sb, conversionContext );
             sb.append( ".parse( <SOURCE> )" );
             return sb.toString();
diff --git a/processor/src/main/java/org/mapstruct/ap/internal/conversion/BigIntegerToStringConversion.java b/processor/src/main/java/org/mapstruct/ap/internal/conversion/BigIntegerToStringConversion.java
index 9cb1cf41c..df0a48a67 100644
--- a/processor/src/main/java/org/mapstruct/ap/internal/conversion/BigIntegerToStringConversion.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/conversion/BigIntegerToStringConversion.java
@@ -47,7 +47,7 @@ public class BigIntegerToStringConversion extends AbstractNumberToStringConversi
     public String getFromExpression(ConversionContext conversionContext) {
         if ( requiresDecimalFormat( conversionContext ) ) {
             StringBuilder sb = new StringBuilder();
-            sb.append( "( (" + bigDecimal( conversionContext ) + ") " );
+            sb.append( "( (" ).append( bigDecimal( conversionContext ) ).append( ") " );
             appendDecimalFormatter( sb, conversionContext );
             sb.append( ".parse( <SOURCE> )" );
             sb.append( " ).toBigInteger()" );
diff --git a/processor/src/main/java/org/mapstruct/ap/internal/model/AbstractMappingMethodBuilder.java b/processor/src/main/java/org/mapstruct/ap/internal/model/AbstractMappingMethodBuilder.java
index c23dd5043..7329df5ab 100644
--- a/processor/src/main/java/org/mapstruct/ap/internal/model/AbstractMappingMethodBuilder.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/model/AbstractMappingMethodBuilder.java
@@ -130,9 +130,7 @@ public abstract class AbstractMappingMethodBuilder<B extends AbstractMappingMeth
                         ctx.getElementUtils(),
                         ctx.getTypeFactory(),
                         ctx.getMessager() );
-        List<Annotation> annotations = new ArrayList<>();
-        annotations.addAll( additionalAnnotationsBuilder.getProcessedAnnotations( method.getExecutable() ) );
-        return annotations;
+        return new ArrayList<>( additionalAnnotationsBuilder.getProcessedAnnotations( method.getExecutable() ) );
     }
 
 }
diff --git a/processor/src/main/java/org/mapstruct/ap/internal/model/BeanMappingMethod.java b/processor/src/main/java/org/mapstruct/ap/internal/model/BeanMappingMethod.java
index 11245b337..00e1d9f9f 100644
--- a/processor/src/main/java/org/mapstruct/ap/internal/model/BeanMappingMethod.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/model/BeanMappingMethod.java
@@ -266,9 +266,7 @@ public class BeanMappingMethod extends NormalTypeMappingMethod {
 
                 Map<String, ReadAccessor> readAccessors = sourceParameter.getType().getPropertyReadAccessors();
 
-                for ( Entry<String, ReadAccessor> entry : readAccessors.entrySet() ) {
-                    unprocessedSourceProperties.put( entry.getKey(), entry.getValue() );
-                }
+                unprocessedSourceProperties.putAll( readAccessors );
             }
 
             // get bean mapping (when specified as annotation )
@@ -499,7 +497,7 @@ public class BeanMappingMethod extends NormalTypeMappingMethod {
                     new ArrayList<>( mappingSourceType.getPermittedSubclasses() );
                 method.getOptions().getSubclassMappings().forEach( subClassOption -> {
                     for (Iterator<? extends TypeMirror> iterator = unusedPermittedSubclasses.iterator();
-                                   iterator.hasNext(); ) {
+                         iterator.hasNext(); ) {
                         if ( ctx.getTypeUtils().isSameType( iterator.next(), subClassOption.getSource() ) ) {
                             iterator.remove();
                         }
diff --git a/processor/src/main/java/org/mapstruct/ap/internal/model/NestedTargetPropertyMappingHolder.java b/processor/src/main/java/org/mapstruct/ap/internal/model/NestedTargetPropertyMappingHolder.java
index b7bfc6978..20825c2dd 100644
--- a/processor/src/main/java/org/mapstruct/ap/internal/model/NestedTargetPropertyMappingHolder.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/model/NestedTargetPropertyMappingHolder.java
@@ -607,7 +607,7 @@ public class NestedTargetPropertyMappingHolder {
          * @param hasNoMappings parameter indicating whether there were any extracted mappings for this target property
          * @param sourceParameter the source parameter for which the grouping is being done
          *
-         * @return a list with valid single target references
+         * @return a set with valid single target references
          */
         private Set<MappingReference> extractSingleTargetReferencesToUseAndPopulateSourceParameterMappings(
             Set<MappingReference> singleTargetReferences, Set<MappingReference> sourceParameterMappings,
diff --git a/processor/src/main/java/org/mapstruct/ap/internal/model/PropertyMapping.java b/processor/src/main/java/org/mapstruct/ap/internal/model/PropertyMapping.java
index bedb37cc8..b81cf5544 100644
--- a/processor/src/main/java/org/mapstruct/ap/internal/model/PropertyMapping.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/model/PropertyMapping.java
@@ -1115,7 +1115,7 @@ public class PropertyMapping extends ModelElement {
         this.targetType = targetType;
 
         this.assignment = assignment;
-        this.dependsOn = dependsOn != null ? dependsOn : Collections.<String>emptySet();
+        this.dependsOn = dependsOn != null ? dependsOn : Collections.emptySet();
         this.defaultValueAssignment = defaultValueAssignment;
         this.constructorMapping = constructorMapping;
     }
diff --git a/processor/src/main/java/org/mapstruct/ap/internal/model/common/DateFormatValidatorFactory.java b/processor/src/main/java/org/mapstruct/ap/internal/model/common/DateFormatValidatorFactory.java
index 09e4957aa..4d54f3c3e 100755
--- a/processor/src/main/java/org/mapstruct/ap/internal/model/common/DateFormatValidatorFactory.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/model/common/DateFormatValidatorFactory.java
@@ -61,13 +61,8 @@ final class DateFormatValidatorFactory {
             dateFormatValidator = new JodaTimeDateFormatValidator();
         }
         else {
-            dateFormatValidator = new DateFormatValidator() {
-                @Override
-                public DateFormatValidationResult validate(String dateFormat) {
-                    return new DateFormatValidationResult( true, Message.GENERAL_UNSUPPORTED_DATE_FORMAT_CHECK,
-                                                           sourceType, targetType );
-                }
-            };
+            dateFormatValidator = dateFormat -> new DateFormatValidationResult(
+                    true, Message.GENERAL_UNSUPPORTED_DATE_FORMAT_CHECK, sourceType, targetType );
         }
         return dateFormatValidator;
 
diff --git a/processor/src/main/java/org/mapstruct/ap/internal/model/common/Type.java b/processor/src/main/java/org/mapstruct/ap/internal/model/common/Type.java
index 933f1f6ce..a6d942748 100644
--- a/processor/src/main/java/org/mapstruct/ap/internal/model/common/Type.java
+++ b/processor/src/main/java/org/mapstruct/ap/internal/model/common/Type.java
@@ -684,10 +684,9 @@ public class Type extends ModelElement implements Comparable<Type> {
      */
     public Map<String, ReadAccessor> getPropertyReadAccessors() {
         if ( readAccessors == null ) {
-            Map<String, ReadAccessor> modifiableGetters = new LinkedHashMap<>();
 
             Map<String, ReadAccessor> recordAccessors = filters.recordAccessorsIn( getRecordComponents() );
-            modifiableGetters.putAll( recordAccessors );
+            Map<String, ReadAccessor> modifiableGetters = new LinkedHashMap<>(recordAccessors);
 
             List<ReadAccessor> getterList = filters.getterMethodsIn( getAllMethods() );
             for ( ReadAccessor getter : getterList ) {
diff --git a/processor/src/test/java/org/mapstruct/ap/test/builder/lifecycle/MappingContext.java b/processor/src/test/java/org/mapstruct/ap/test/builder/lifecycle/MappingContext.java
index 079be90a8..2065bad47 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/builder/lifecycle/MappingContext.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/builder/lifecycle/MappingContext.java
@@ -18,7 +18,7 @@ import org.mapstruct.TargetType;
  */
 public class MappingContext {
 
-    private final List<String> invokedMethods = new ArrayList<String>();
+    private final List<String> invokedMethods = new ArrayList<>();
 
     @BeforeMapping
     public void beforeWithoutParameters() {
diff --git a/processor/src/test/java/org/mapstruct/ap/test/builder/parentchild/ParentChildBuilderTest.java b/processor/src/test/java/org/mapstruct/ap/test/builder/parentchild/ParentChildBuilderTest.java
index dd45573a5..562770a2b 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/builder/parentchild/ParentChildBuilderTest.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/builder/parentchild/ParentChildBuilderTest.java
@@ -26,7 +26,7 @@ public class ParentChildBuilderTest {
     public void testParentChildBuilderMapper() {
         final MutableParent parent = new MutableParent();
         parent.setCount( 4 );
-        parent.setChildren( new ArrayList<MutableChild>() );
+        parent.setChildren( new ArrayList<>() );
         parent.getChildren().add( new MutableChild( "Phineas" ) );
         parent.getChildren().add( new MutableChild( "Ferb" ) );
 
diff --git a/processor/src/test/java/org/mapstruct/ap/test/builder/simple/SimpleImmutablePerson.java b/processor/src/test/java/org/mapstruct/ap/test/builder/simple/SimpleImmutablePerson.java
index daa3dfad0..2fe2c8ded 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/builder/simple/SimpleImmutablePerson.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/builder/simple/SimpleImmutablePerson.java
@@ -22,7 +22,7 @@ public class SimpleImmutablePerson {
         this.job = builder.job;
         this.city = builder.city;
         this.address = builder.address;
-        this.children = new ArrayList<String>( builder.children );
+        this.children = new ArrayList<>(builder.children);
     }
 
     public static Builder builder() {
@@ -59,7 +59,7 @@ public class SimpleImmutablePerson {
         private String job;
         private String city;
         private String address;
-        private List<String> children = new ArrayList<String>();
+        private List<String> children = new ArrayList<>();
 
         public Builder age(int age) {
             this.age = age;
diff --git a/processor/src/test/java/org/mapstruct/ap/test/callbacks/BaseMapper.java b/processor/src/test/java/org/mapstruct/ap/test/callbacks/BaseMapper.java
index bee462acc..4e02045ed 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/callbacks/BaseMapper.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/callbacks/BaseMapper.java
@@ -24,7 +24,7 @@ public abstract class BaseMapper {
     @Qualified
     public abstract Target sourceToTargetQualified(Source source);
 
-    private static final List<Invocation> INVOCATIONS = new ArrayList<Invocation>();
+    private static final List<Invocation> INVOCATIONS = new ArrayList<>();
 
     @BeforeMapping
     public void noArgsBeforeMapping() {
diff --git a/processor/src/test/java/org/mapstruct/ap/test/callbacks/CallbackMethodTest.java b/processor/src/test/java/org/mapstruct/ap/test/callbacks/CallbackMethodTest.java
index 7026a335d..825b35915 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/callbacks/CallbackMethodTest.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/callbacks/CallbackMethodTest.java
@@ -111,7 +111,7 @@ public class CallbackMethodTest {
         SourceEnum source = SourceEnum.B;
         TargetEnum target = SourceTargetMapper.INSTANCE.toTargetEnum( source );
 
-        List<Invocation> invocations = new ArrayList<Invocation>();
+        List<Invocation> invocations = new ArrayList<>();
         invocations.addAll( allBeforeMappingMethods( source, target, TargetEnum.class ) );
         invocations.addAll( allAfterMappingMethods( source, target, TargetEnum.class ) );
 
diff --git a/processor/src/test/java/org/mapstruct/ap/test/callbacks/ClassContainingCallbacks.java b/processor/src/test/java/org/mapstruct/ap/test/callbacks/ClassContainingCallbacks.java
index 762247045..2889a4ad3 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/callbacks/ClassContainingCallbacks.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/callbacks/ClassContainingCallbacks.java
@@ -18,7 +18,7 @@ import org.mapstruct.TargetType;
  * @author Andreas Gudian
  */
 public class ClassContainingCallbacks {
-    private static final List<Invocation> INVOCATIONS = new ArrayList<Invocation>();
+    private static final List<Invocation> INVOCATIONS = new ArrayList<>();
 
     @BeforeMapping
     public void noArgsBeforeMapping() {
diff --git a/processor/src/test/java/org/mapstruct/ap/test/callbacks/returning/CallbacksWithReturnValuesTest.java b/processor/src/test/java/org/mapstruct/ap/test/callbacks/returning/CallbacksWithReturnValuesTest.java
index 7d6eaacb7..10d2a29cd 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/callbacks/returning/CallbacksWithReturnValuesTest.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/callbacks/returning/CallbacksWithReturnValuesTest.java
@@ -50,12 +50,7 @@ class CallbacksWithReturnValuesTest {
     @ProcessorTest
     void mappingWithContextCorrectlyResolvesCycles() {
         final AtomicReference<Integer> contextLevel = new AtomicReference<>( null );
-        ContextListener contextListener = new ContextListener() {
-            @Override
-            public void methodCalled(Integer level, String method, Object source, Object target) {
-                contextLevel.set( level );
-            }
-        };
+        ContextListener contextListener = (level, method, source, target) -> contextLevel.set( level );
 
         NodeMapperContext.addContextListener( contextListener );
         try {
diff --git a/processor/src/test/java/org/mapstruct/ap/test/callbacks/returning/NodeMapperContext.java b/processor/src/test/java/org/mapstruct/ap/test/callbacks/returning/NodeMapperContext.java
index 40a1a6393..325778b85 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/callbacks/returning/NodeMapperContext.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/callbacks/returning/NodeMapperContext.java
@@ -19,11 +19,11 @@ import org.mapstruct.TargetType;
  * @author Pascal Grün
  */
 public class NodeMapperContext {
-    private static final ThreadLocal<Integer> LEVEL = new ThreadLocal<Integer>();
-    private static final ThreadLocal<Map<Object, Object>> MAPPING = new ThreadLocal<Map<Object, Object>>();
+    private static final ThreadLocal<Integer> LEVEL = new ThreadLocal<>();
+    private static final ThreadLocal<Map<Object, Object>> MAPPING = new ThreadLocal<>();
 
     /** Only for test-inspection */
-    private static final List<ContextListener> LISTENERS = new CopyOnWriteArrayList<ContextListener>();
+    private static final List<ContextListener> LISTENERS = new CopyOnWriteArrayList<>();
 
     private NodeMapperContext() {
         // Only allow static access
diff --git a/processor/src/test/java/org/mapstruct/ap/test/collection/adder/_target/Target2.java b/processor/src/test/java/org/mapstruct/ap/test/collection/adder/_target/Target2.java
index 850c6ee94..bd6e8f997 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/collection/adder/_target/Target2.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/collection/adder/_target/Target2.java
@@ -16,7 +16,7 @@ import org.mapstruct.ap.test.collection.adder.source.Foo;
  */
 public class Target2 {
 
-    private List<Foo> attributes = new ArrayList<Foo>();
+    private List<Foo> attributes = new ArrayList<>();
 
     public Foo addAttribute( Foo foo ) {
         attributes.add( foo );
diff --git a/processor/src/test/java/org/mapstruct/ap/test/collection/defaultimplementation/NoSetterTarget.java b/processor/src/test/java/org/mapstruct/ap/test/collection/defaultimplementation/NoSetterTarget.java
index 562966dfd..817879fa0 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/collection/defaultimplementation/NoSetterTarget.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/collection/defaultimplementation/NoSetterTarget.java
@@ -15,8 +15,8 @@ import java.util.Map;
  *
  */
 public class NoSetterTarget {
-    private List<String> listValues = new ArrayList<String>();
-    private Map<String, String> mapValues = new HashMap<String, String>();
+    private List<String> listValues = new ArrayList<>();
+    private Map<String, String> mapValues = new HashMap<>();
 
     public List<String> getListValues() {
         return listValues;
diff --git a/processor/src/test/java/org/mapstruct/ap/test/java8stream/Target.java b/processor/src/test/java/org/mapstruct/ap/test/java8stream/Target.java
index 2d63c3f16..49b23530d 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/java8stream/Target.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/java8stream/Target.java
@@ -77,7 +77,7 @@ public class Target {
 
     public List<String> getStringListNoSetter() {
         if ( stringListNoSetter == null ) {
-            stringListNoSetter = new ArrayList<String>();
+            stringListNoSetter = new ArrayList<>();
         }
         return stringListNoSetter;
     }
diff --git a/processor/src/test/java/org/mapstruct/ap/test/nestedbeans/HouseDto.java b/processor/src/test/java/org/mapstruct/ap/test/nestedbeans/HouseDto.java
index 1d92eb7e4..71beedaa9 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/nestedbeans/HouseDto.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/nestedbeans/HouseDto.java
@@ -5,6 +5,8 @@
  */
 package org.mapstruct.ap.test.nestedbeans;
 
+import java.util.Objects;
+
 public class HouseDto {
 
     private String name;
@@ -58,10 +60,10 @@ public class HouseDto {
         if ( year != houseDto.year ) {
             return false;
         }
-        if ( name != null ? !name.equals( houseDto.name ) : houseDto.name != null ) {
+        if ( !Objects.equals( name, houseDto.name ) ) {
             return false;
         }
-        return roof != null ? roof.equals( houseDto.roof ) : houseDto.roof == null;
+        return Objects.equals( roof, houseDto.roof );
 
     }
 
diff --git a/processor/src/test/java/org/mapstruct/ap/test/nestedbeans/maps/AntonymsDictionaryDto.java b/processor/src/test/java/org/mapstruct/ap/test/nestedbeans/maps/AntonymsDictionaryDto.java
index 33ccfbc1c..9ac7913c9 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/nestedbeans/maps/AntonymsDictionaryDto.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/nestedbeans/maps/AntonymsDictionaryDto.java
@@ -6,6 +6,7 @@
 package org.mapstruct.ap.test.nestedbeans.maps;
 
 import java.util.Map;
+import java.util.Objects;
 
 public class AntonymsDictionaryDto {
     private Map<WordDto, WordDto> antonyms;
@@ -36,8 +37,7 @@ public class AntonymsDictionaryDto {
 
         AntonymsDictionaryDto antonymsDictionaryDto = (AntonymsDictionaryDto) o;
 
-        return antonyms != null ? antonyms.equals( antonymsDictionaryDto.antonyms ) :
-            antonymsDictionaryDto.antonyms == null;
+        return Objects.equals( antonyms, antonymsDictionaryDto.antonyms );
 
     }
 
diff --git a/processor/src/test/java/org/mapstruct/ap/test/selection/resulttype/InheritanceSelectionTest.java b/processor/src/test/java/org/mapstruct/ap/test/selection/resulttype/InheritanceSelectionTest.java
index 05245bafe..8cd58f066 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/selection/resulttype/InheritanceSelectionTest.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/selection/resulttype/InheritanceSelectionTest.java
@@ -192,7 +192,7 @@ public class InheritanceSelectionTest {
     })
     public void testShouldSelectResultTypeInCaseOfAmbiguityForMap() {
 
-        Map<AppleDto, AppleDto> source = new HashMap<AppleDto, AppleDto>();
+        Map<AppleDto, AppleDto> source = new HashMap<>();
         source.put( new AppleDto( "GoldenDelicious" ), new AppleDto( "AppleDto" ) );
 
         Map<Apple, Apple> result = FruitFamilyMapper.INSTANCE.mapToGoldenDeliciousMap( source );
diff --git a/processor/src/test/java/org/mapstruct/ap/test/source/constants/Target.java b/processor/src/test/java/org/mapstruct/ap/test/source/constants/Target.java
index 98ca13eb0..7897fe2bd 100644
--- a/processor/src/test/java/org/mapstruct/ap/test/source/constants/Target.java
+++ b/processor/src/test/java/org/mapstruct/ap/test/source/constants/Target.java
@@ -20,7 +20,7 @@ public class Target {
     private int integerConstant;
     private Long longWrapperConstant;
     private Date dateConstant;
-    private List<String> nameConstants = new ArrayList<String>();
+    private List<String> nameConstants = new ArrayList<>();
     private CountryEnum country;
 
     public String getPropertyThatShouldBeMapped() {
diff --git a/processor/src/test/java/org/mapstruct/ap/testutil/assertions/JavaFileAssert.java b/processor/src/test/java/org/mapstruct/ap/testutil/assertions/JavaFileAssert.java
index 2bcfbd94d..e6eabd9f8 100644
--- a/processor/src/test/java/org/mapstruct/ap/testutil/assertions/JavaFileAssert.java
+++ b/processor/src/test/java/org/mapstruct/ap/testutil/assertions/JavaFileAssert.java
@@ -59,7 +59,7 @@ public class JavaFileAssert extends FileAssert {
             return Assertions.assertThat( FileUtils.readFileToString( actual, StandardCharsets.UTF_8 ) );
         }
         catch ( IOException e ) {
-            failWithMessage( "Unable to read" + actual.toString() + ". Exception: " + e.getMessage() );
+            failWithMessage( "Unable to read" + actual + ". Exception: " + e.getMessage() );
         }
         return null;
     }
diff --git a/processor/src/test/java/org/mapstruct/ap/testutil/compilation/model/DiagnosticDescriptor.java b/processor/src/test/java/org/mapstruct/ap/testutil/compilation/model/DiagnosticDescriptor.java
index 94dda7470..ecfec14a1 100644
--- a/processor/src/test/java/org/mapstruct/ap/testutil/compilation/model/DiagnosticDescriptor.java
+++ b/processor/src/test/java/org/mapstruct/ap/testutil/compilation/model/DiagnosticDescriptor.java
@@ -131,7 +131,7 @@ public class DiagnosticDescriptor {
 
         //Make the URI absolute in case it isn't (the case with JDK 6)
         try {
-            return new URI( "file:" + uri.toString() );
+            return new URI( "file:" + uri );
         }
         catch ( URISyntaxException e ) {
             throw new RuntimeException( e );
@@ -189,7 +189,7 @@ public class DiagnosticDescriptor {
         if ( kind != other.kind ) {
             return false;
         }
-        if ( line != other.line ) {
+        if ( !Objects.equals( line, other.line ) ) {
             return false;
         }
         if ( !Objects.equals( message, other.message ) ) {
diff --git a/processor/src/test/java/org/mapstruct/ap/testutil/runner/JdkCompilingExtension.java b/processor/src/test/java/org/mapstruct/ap/testutil/runner/JdkCompilingExtension.java
index 7b44a4733..5185bfb7e 100644
--- a/processor/src/test/java/org/mapstruct/ap/testutil/runner/JdkCompilingExtension.java
+++ b/processor/src/test/java/org/mapstruct/ap/testutil/runner/JdkCompilingExtension.java
@@ -135,7 +135,7 @@ class JdkCompilingExtension extends CompilingExtension {
             // The JDK 8+ compilers report all ERROR diagnostics properly. Also when there are multiple per line.
             return expectedDiagnostics;
         }
-        List<DiagnosticDescriptor> filtered = new ArrayList<DiagnosticDescriptor>( expectedDiagnostics.size() );
+        List<DiagnosticDescriptor> filtered = new ArrayList<>(expectedDiagnostics.size());
 
         // The JDK 8 compiler only reports the first message of kind ERROR that is reported for one source file line,
         // so we filter out the surplus diagnostics. The input list is already sorted by file name and line number,
diff --git a/processor/src/test/java/org/mapstruct/ap/testutil/runner/ModifiableURLClassLoader.java b/processor/src/test/java/org/mapstruct/ap/testutil/runner/ModifiableURLClassLoader.java
index 9cc41fe13..2dd5d5b8e 100644
--- a/processor/src/test/java/org/mapstruct/ap/testutil/runner/ModifiableURLClassLoader.java
+++ b/processor/src/test/java/org/mapstruct/ap/testutil/runner/ModifiableURLClassLoader.java
@@ -31,7 +31,7 @@ final class ModifiableURLClassLoader extends URLClassLoader {
         tryRegisterAsParallelCapable();
     }
 
-    private final ConcurrentMap<URL, URL> addedURLs = new ConcurrentHashMap<URL, URL>();
+    private final ConcurrentMap<URL, URL> addedURLs = new ConcurrentHashMap<>();
 
     ModifiableURLClassLoader(ClassLoader parent) {
         super( new URL[] { }, parent );