[MNG-6847] Explicit type can be replaced by the diamond operator

This closes #315

maven-artifact/src/main/java/org/apache/maven/artifact/resolver/MultipleArtifactsNotFoundException.java

@@ -41,7 +41,7 @@ public MultipleArtifactsNotFoundException( Artifact originatingArtifact,
                                                List<Artifact> missingArtifacts,
                                                List<ArtifactRepository> remoteRepositories )
     {
-        this( originatingArtifact, new ArrayList<Artifact>(), missingArtifacts, remoteRepositories );
+        this( originatingArtifact, new ArrayList<>(), missingArtifacts, remoteRepositories );
     }
 
     /**

maven-artifact/src/main/java/org/apache/maven/artifact/versioning/VersionRange.java

@@ -37,10 +37,10 @@
 public class VersionRange
 {
     private static final Map<String, VersionRange> CACHE_SPEC =
-        Collections.<String, VersionRange>synchronizedMap( new WeakHashMap<String, VersionRange>() );
+        Collections.synchronizedMap( new WeakHashMap<>() );
 
     private static final Map<String, VersionRange> CACHE_VERSION =
-                    Collections.<String, VersionRange>synchronizedMap( new WeakHashMap<String, VersionRange>() );
+                    Collections.synchronizedMap( new WeakHashMap<>() );
 
     private final ArtifactVersion recommendedVersion;
 

maven-builder-support/src/main/java/org/apache/maven/building/DefaultProblemCollector.java

@@ -38,7 +38,7 @@ class DefaultProblemCollector
 
     DefaultProblemCollector( List<Problem> problems )
     {
-        this.problems = ( problems != null ) ? problems : new ArrayList<Problem>();
+        this.problems = ( problems != null ) ? problems : new ArrayList<>();
     }
 
     @Override

maven-compat/src/main/java/org/apache/maven/artifact/resolver/DefaultArtifactResolver.java

@@ -116,7 +116,7 @@ public void execute( Runnable command )
         else
         {
             executor = new ThreadPoolExecutor( threads, threads, 3, TimeUnit.SECONDS,
-                                               new LinkedBlockingQueue<Runnable>(), new DaemonThreadCreator() );
+                    new LinkedBlockingQueue<>(), new DaemonThreadCreator() );
         }
     }
 

maven-core/src/main/java/org/apache/maven/DuplicateProjectException.java

@@ -45,7 +45,7 @@ public DuplicateProjectException( String message, Map<String, List<File>> collis
     {
         super( message, (File) null );
 
-        this.collisions = ( collisions != null ) ? collisions : new LinkedHashMap<String, List<File>>();
+        this.collisions = ( collisions != null ) ? collisions : new LinkedHashMap<>();
     }
 
     /**

maven-core/src/main/java/org/apache/maven/execution/DefaultMavenExecutionRequestPopulator.java

@@ -78,7 +78,7 @@ public MavenExecutionRequest populateFromToolchains( MavenExecutionRequest reque
             {
                 if ( !groupedToolchains.containsKey( model.getType() ) )
                 {
-                    groupedToolchains.put( model.getType(), new ArrayList<ToolchainModel>() );
+                    groupedToolchains.put( model.getType(), new ArrayList<>() );
                 }
 
                 groupedToolchains.get( model.getType() ).add( model );

maven-core/src/main/java/org/apache/maven/execution/DefaultMavenExecutionResult.java

@@ -41,7 +41,7 @@ public class DefaultMavenExecutionResult
     private final List<Throwable> exceptions = new CopyOnWriteArrayList<>();
 
     private final Map<MavenProject, BuildSummary> buildSummaries =
-        Collections.synchronizedMap( new IdentityHashMap<MavenProject, BuildSummary>() );
+        Collections.synchronizedMap( new IdentityHashMap<>() );
 
     public MavenExecutionResult setProject( MavenProject project )
     {
@@ -65,7 +65,7 @@ public MavenExecutionResult setTopologicallySortedProjects( List<MavenProject> t
     public List<MavenProject> getTopologicallySortedProjects()
     {
         return null == topologicallySortedProjects
-                   ? Collections.<MavenProject>emptyList()
+                   ? Collections.emptyList()
                    : Collections.unmodifiableList( topologicallySortedProjects );
 
     }

maven-core/src/main/java/org/apache/maven/graph/FilteredProjectDependencyGraph.java

@@ -56,7 +56,7 @@ class FilteredProjectDependencyGraph
         this.projectDependencyGraph =
                 Objects.requireNonNull( projectDependencyGraph, "projectDependencyGraph cannot be null" );
 
-        this.whiteList = new IdentityHashMap<MavenProject, Object>();
+        this.whiteList = new IdentityHashMap<>();
 
         for ( MavenProject project : whiteList )
         {

maven-core/src/main/java/org/apache/maven/lifecycle/internal/DefaultLifecycleExecutionPlanCalculator.java

@@ -179,7 +179,7 @@ public void setupMojoExecution( MavenSession session, MavenProject project, Mojo
 
         finalizeMojoConfiguration( mojoExecution );
 
-        calculateForkedExecutions( mojoExecution, session, project, new HashSet<MojoDescriptor>() );
+        calculateForkedExecutions( mojoExecution, session, project, new HashSet<>() );
     }
 
     public List<MojoExecution> calculateMojoExecutions( MavenSession session, MavenProject project, List<Object> tasks )
@@ -331,7 +331,7 @@ public void calculateForkedExecutions( MojoExecution mojoExecution, MavenSession
         PluginDescriptorParsingException, NoPluginFoundForPrefixException, InvalidPluginDescriptorException,
         LifecyclePhaseNotFoundException, LifecycleNotFoundException, PluginVersionResolutionException
     {
-        calculateForkedExecutions( mojoExecution, session, session.getCurrentProject(), new HashSet<MojoDescriptor>() );
+        calculateForkedExecutions( mojoExecution, session, session.getCurrentProject(), new HashSet<>() );
     }
 
     private void calculateForkedExecutions( MojoExecution mojoExecution, MavenSession session, MavenProject project,

maven-core/src/main/java/org/apache/maven/lifecycle/internal/DependencyContext.java

@@ -62,8 +62,8 @@ public DependencyContext( MavenProject project, Collection<String> scopesToColle
         this.project = project;
         scopesToCollectForCurrentProject = scopesToCollect;
         scopesToResolveForCurrentProject = scopesToResolve;
-        scopesToCollectForAggregatedProjects = Collections.synchronizedSet( new TreeSet<String>() );
+        scopesToCollectForAggregatedProjects = Collections.synchronizedSet( new TreeSet<>() );
-        scopesToResolveForAggregatedProjects = Collections.synchronizedSet( new TreeSet<String>() );
+        scopesToResolveForAggregatedProjects = Collections.synchronizedSet( new TreeSet<>() );
     }
 
     public MavenProject getProject()

maven-core/src/main/java/org/apache/maven/lifecycle/internal/LifecycleModuleBuilder.java

@@ -22,7 +22,6 @@
 import java.util.HashSet;
 import java.util.List;
 
-import org.apache.maven.artifact.Artifact;
 import org.apache.maven.execution.BuildSuccess;
 import org.apache.maven.execution.ExecutionEvent;
 import org.apache.maven.execution.MavenSession;
@@ -108,7 +107,7 @@ public void buildProject( MavenSession session, MavenSession rootSession, Reacto
             eventCatapult.fire( ExecutionEvent.Type.ProjectStarted, session, null );
 
             MavenExecutionPlan executionPlan =
-                builderCommon.resolveBuildPlan( session, currentProject, taskSegment, new HashSet<Artifact>() );
+                builderCommon.resolveBuildPlan( session, currentProject, taskSegment, new HashSet<>() );
             List<MojoExecution> mojoExecutions = executionPlan.getMojoExecutions();
 
             projectExecutionListener.beforeProjectLifecycleExecution( new ProjectExecutionEvent( session,

maven-core/src/main/java/org/apache/maven/lifecycle/internal/ReactorBuildStatus.java

@@ -37,7 +37,7 @@ public class ReactorBuildStatus
 {
     private final ProjectDependencyGraph projectDependencyGraph;
 
-    private final Collection<String> blackListedProjects = Collections.synchronizedSet( new HashSet<String>() );
+    private final Collection<String> blackListedProjects = Collections.synchronizedSet( new HashSet<>() );
 
     private volatile boolean halted = false;
 

maven-core/src/main/java/org/apache/maven/lifecycle/internal/builder/multithreaded/ThreadOutputMuxer.java

@@ -56,7 +56,7 @@ public class ThreadOutputMuxer
 
     private final PrintStream defaultPrintStream = new PrintStream( defaultOutputStreamForUnknownData );
 
-    private final Set<ProjectSegment> completedBuilds = Collections.synchronizedSet( new HashSet<ProjectSegment>() );
+    private final Set<ProjectSegment> completedBuilds = Collections.synchronizedSet( new HashSet<>() );
 
     private volatile ProjectSegment currentBuild;
 

maven-core/src/main/java/org/apache/maven/project/DefaultProjectBuilder.java

@@ -185,8 +185,8 @@ private ProjectBuildingResult build( File pomFile, ModelSource modelSource, Inte
 
                 modelProblems = result.getProblems();
 
-                initProject( project, Collections.<String, MavenProject>emptyMap(), true,
+                initProject( project, Collections.emptyMap(), true,
-                             result, new HashMap<File, Boolean>(), projectBuildingRequest );
+                             result, new HashMap<>(), projectBuildingRequest );
             }
             else if ( projectBuildingRequest.isResolveDependencies() )
             {
@@ -374,7 +374,7 @@ public List<ProjectBuildingResult> build( List<File> pomFiles, boolean recursive
         Map<String, MavenProject> projectIndex = new HashMap<>( 256 );
 
         boolean noErrors =
-            build( results, interimResults, projectIndex, pomFiles, new LinkedHashSet<File>(), true, recursive,
+            build( results, interimResults, projectIndex, pomFiles, new LinkedHashSet<>(), true, recursive,
                    config );
 
         populateReactorModelPool( modelPool, interimResults );
@@ -384,8 +384,8 @@ public List<ProjectBuildingResult> build( List<File> pomFiles, boolean recursive
         try
         {
             noErrors =
-                build( results, new ArrayList<MavenProject>(), projectIndex, interimResults, request,
+                build( results, new ArrayList<>(), projectIndex, interimResults, request,
-                       new HashMap<File, Boolean>(), config.session ) && noErrors;
+                        new HashMap<>(), config.session ) && noErrors;
         }
         finally
         {
@@ -465,7 +465,7 @@ private boolean build( List<ProjectBuildingResult> results, List<InterimResult>
         try
         {
             // first pass: build without building parent.
-            initProject( project, projectIndex, false, result, new HashMap<File, Boolean>( 0 ), config.request );
+            initProject( project, projectIndex, false, result, new HashMap<>( 0 ), config.request );
         }
         catch ( InvalidArtifactRTException iarte )
         {

maven-core/src/main/java/org/apache/maven/project/MavenProject.java

@@ -175,7 +175,7 @@ public class MavenProject
 
     private DependencyFilter extensionDependencyFilter;
 
-    private final Set<String> lifecyclePhases = Collections.synchronizedSet( new LinkedHashSet<String>() );
+    private final Set<String> lifecyclePhases = Collections.synchronizedSet( new LinkedHashSet<>() );
 
     public MavenProject()
     {

maven-core/src/main/java/org/apache/maven/project/artifact/DefaultMavenMetadataCache.java

@@ -220,14 +220,14 @@ public class CacheRecord
         {
             this.pomArtifact = ArtifactUtils.copyArtifact( pomArtifact );
             this.relocatedArtifact = ArtifactUtils.copyArtifactSafe( relocatedArtifact );
-            this.artifacts = ArtifactUtils.copyArtifacts( artifacts, new ArrayList<Artifact>() );
+            this.artifacts = ArtifactUtils.copyArtifacts( artifacts, new ArrayList<>() );
             this.remoteRepositories = new ArrayList<>( remoteRepositories );
 
             this.managedVersions = managedVersions;
             if ( managedVersions != null )
             {
                 this.managedVersions =
-                    ArtifactUtils.copyArtifacts( managedVersions, new LinkedHashMap<String, Artifact>() );
+                    ArtifactUtils.copyArtifacts( managedVersions, new LinkedHashMap<>() );
             }
 
             File pomFile = pomArtifact.getFile();
@@ -310,11 +310,11 @@ public ResolutionGroup get( Artifact artifact, boolean resolveManagedVersions, A
             Artifact pomArtifact = ArtifactUtils.copyArtifact( cacheRecord.getArtifact() );
             Artifact relocatedArtifact = ArtifactUtils.copyArtifactSafe( cacheRecord.getRelocatedArtifact() );
             Set<Artifact> artifacts =
-                ArtifactUtils.copyArtifacts( cacheRecord.getArtifacts(), new LinkedHashSet<Artifact>() );
+                ArtifactUtils.copyArtifacts( cacheRecord.getArtifacts(), new LinkedHashSet<>() );
             Map<String, Artifact> managedVersions = cacheRecord.getManagedVersions();
             if ( managedVersions != null )
             {
-                managedVersions = ArtifactUtils.copyArtifacts( managedVersions, new LinkedHashMap<String, Artifact>() );
+                managedVersions = ArtifactUtils.copyArtifacts( managedVersions, new LinkedHashMap<>() );
             }
             return new ResolutionGroup( pomArtifact, relocatedArtifact, artifacts, managedVersions,
                                         cacheRecord.getRemoteRepositories() );

maven-core/src/main/java/org/apache/maven/toolchain/DefaultToolchainManager.java

@@ -129,7 +129,7 @@ Map<String, Object> retrieveContext( MavenSession session )
             }
         }
 
-        return ( context != null ) ? context : new HashMap<String, Object>();
+        return ( context != null ) ? context : new HashMap<>();
     }
 
     public static final String getStorageKey( String type )

maven-core/src/main/java/org/apache/maven/toolchain/building/DefaultToolchainsBuildingResult.java

@@ -48,7 +48,7 @@ public class DefaultToolchainsBuildingResult
     public DefaultToolchainsBuildingResult( PersistedToolchains effectiveToolchains, List<Problem> problems )
     {
         this.effectiveToolchains = effectiveToolchains;
-        this.problems = ( problems != null ) ? problems : new ArrayList<Problem>();
+        this.problems = ( problems != null ) ? problems : new ArrayList<>();
     }
 
     @Override

maven-core/src/test/java/org/apache/maven/lifecycle/internal/BuilderCommonTest.java

@@ -45,7 +45,7 @@ public void testResolveBuildPlan()
         final BuilderCommon builderCommon = getBuilderCommon();
         final MavenExecutionPlan plan =
             builderCommon.resolveBuildPlan( session1, ProjectDependencyGraphStub.A, taskSegment1,
-                                            new HashSet<Artifact>() );
+                    new HashSet<>() );
         assertEquals( LifecycleExecutionPlanCalculatorStub.getProjectAExceutionPlan().size(), plan.size() );
 
     }

maven-core/src/test/java/org/apache/maven/lifecycle/internal/stub/CompletionServiceStub.java

@@ -33,7 +33,7 @@ public class CompletionServiceStub
     implements CompletionService<ProjectSegment>
 {
     List<FutureTask<ProjectSegment>> projectBuildFutureTasks =
-        Collections.synchronizedList( new ArrayList<FutureTask<ProjectSegment>>() );
+        Collections.synchronizedList(new ArrayList<>() );
 
     final boolean finishImmediately;
 

maven-core/src/test/java/org/apache/maven/lifecycle/internal/stub/MojoExecutorStub.java

@@ -36,7 +36,7 @@ public class MojoExecutorStub
     extends MojoExecutor
 { // This is being lazy instead of making interface
 
-    public List<MojoExecution> executions = Collections.synchronizedList( new ArrayList<MojoExecution>() );
+    public List<MojoExecution> executions = Collections.synchronizedList(new ArrayList<>() );
 
     @Override
     public void execute( MavenSession session, MojoExecution mojoExecution, ProjectIndex projectIndex,

maven-embedder/src/main/java/org/apache/maven/cli/transfer/ConsoleMavenTransferListener.java

@@ -41,7 +41,7 @@ public class ConsoleMavenTransferListener
 {
 
     private Map<TransferResource, Long> transfers = Collections.synchronizedMap(
-                                                        new LinkedHashMap<TransferResource, Long>() );
+            new LinkedHashMap<>() );
 
     private boolean printResourceNames;
     private int lastLength;

maven-model-builder/src/main/java/org/apache/maven/model/building/DefaultModelBuilder.java

@@ -437,7 +437,7 @@ else if ( !parentIds.add( parentData.getId() ) )
     public ModelBuildingResult build( ModelBuildingRequest request, ModelBuildingResult result )
         throws ModelBuildingException
     {
-        return build( request, result, new LinkedHashSet<String>() );
+        return build( request, result, new LinkedHashSet<>() );
     }
 
     private ModelBuildingResult build( ModelBuildingRequest request, ModelBuildingResult result,

maven-resolver-provider/src/test/java/org/apache/maven/repository/internal/RemoteSnapshotMetadataTest.java

@@ -75,7 +75,7 @@ public void gregorianCalendarIsUsed()
         String datePart = ts.replaceAll( "\\..*", "" );
 
         /* Allow for this test running across midnight */
-        Set<String> expected = new HashSet<String>( Arrays.asList( dateBefore, dateAfter ) );
+        Set<String> expected = new HashSet<>( Arrays.asList( dateBefore, dateAfter ) );
         assertTrue( "Expected " + datePart + " to be in " + expected,
                 expected.contains( datePart ) );
     }

maven-settings-builder/src/main/java/org/apache/maven/settings/building/DefaultSettingsBuildingResult.java

@@ -40,7 +40,7 @@ class DefaultSettingsBuildingResult
     DefaultSettingsBuildingResult( Settings effectiveSettings, List<SettingsProblem> problems )
     {
         this.effectiveSettings = effectiveSettings;
-        this.problems = ( problems != null ) ? problems : new ArrayList<SettingsProblem>();
+        this.problems = ( problems != null ) ? problems : new ArrayList<>();
     }
 
     @Override

maven-settings-builder/src/main/java/org/apache/maven/settings/building/DefaultSettingsProblemCollector.java

@@ -39,7 +39,7 @@ class DefaultSettingsProblemCollector
 
     DefaultSettingsProblemCollector( List<SettingsProblem> problems )
     {
-        this.problems = ( problems != null ) ? problems : new ArrayList<SettingsProblem>();
+        this.problems = ( problems != null ) ? problems : new ArrayList<>();
     }
 
     public List<SettingsProblem> getProblems()

maven-settings-builder/src/main/java/org/apache/maven/settings/crypto/DefaultSettingsDecryptionResult.java

@@ -43,9 +43,9 @@ class DefaultSettingsDecryptionResult
 
     DefaultSettingsDecryptionResult( List<Server> servers, List<Proxy> proxies, List<SettingsProblem> problems )
     {
-        this.servers = ( servers != null ) ? servers : new ArrayList<Server>();
+        this.servers = ( servers != null ) ? servers : new ArrayList<>();
-        this.proxies = ( proxies != null ) ? proxies : new ArrayList<Proxy>();
+        this.proxies = ( proxies != null ) ? proxies : new ArrayList<>();
-        this.problems = ( problems != null ) ? problems : new ArrayList<SettingsProblem>();
+        this.problems = ( problems != null ) ? problems : new ArrayList<>();
     }
 
     @Override