Fix override method proposal

org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/contentassist/CompletionProposalReplacementProvider.java

@@ -319,7 +319,9 @@ private void appendMethodOverrideReplacement(StringBuilder completionBuffer, Com
 					completion);
 			String replacement = overrider.updateReplacementString(document, offset, importRewrite,
 					client.isCompletionSnippetsSupported());
-			completionBuffer.append(replacement);
+			if (replacement != null) {
+				completionBuffer.append(replacement);
+			}
 		} catch (BadLocationException | CoreException e) {
 			JavaLanguageServerPlugin.logException("Failed to compute override replacement", e);
 		}

org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/contentassist/OverrideCompletionProposal.java

@@ -63,6 +63,7 @@ public class OverrideCompletionProposal {
 	private String fMethodName;
 	private String[] fParamTypes;
 	private ICompilationUnit fCompilationUnit;
+	private String replacementString;
 
 	public OverrideCompletionProposal(ICompilationUnit cu, String methodName, String[] paramTypes, String completionProposal) {
 		this.fCompilationUnit = cu;
@@ -74,6 +75,10 @@ public OverrideCompletionProposal(ICompilationUnit cu, String methodName, String
 		fParamTypes= paramTypes;
 		fMethodName= methodName;
 		fJavaProject= cu.getJavaProject();
+		StringBuilder buffer = new StringBuilder();
+		buffer.append(completionProposal);
+		buffer.append(" {};");
+		replacementString = buffer.toString();
 	}
 
 	private CompilationUnit getRecoveredAST(IDocument document, int offset, Document recoveredDocument) {
@@ -165,6 +170,9 @@ public String updateReplacementString(IDocument document, int offset, ImportRewr
 				}
 			}
 		}
+		if (result == null) {
+			return replacementString;
+		}
 		return result;
 	}
 

org.eclipse.jdt.ls.tests/projects/eclipse/testnullable/.classpath

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<classpath>
+	<classpathentry kind="src" path="src"/>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.8"/>
+	<classpathentry kind="output" path="bin"/>
+</classpath>

org.eclipse.jdt.ls.tests/projects/eclipse/testnullable/.project

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>testnullable</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.jdt.core.javabuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.jdt.core.javanature</nature>
+	</natures>
+</projectDescription>

org.eclipse.jdt.ls.tests/projects/eclipse/testnullable/.settings/org.eclipse.jdt.core.prefs

@@ -0,0 +1,117 @@
+eclipse.preferences.version=1
+org.eclipse.jdt.core.compiler.annotation.inheritNullAnnotations=disabled
+org.eclipse.jdt.core.compiler.annotation.missingNonNullByDefaultAnnotation=ignore
+org.eclipse.jdt.core.compiler.annotation.nonnull=org.eclipse.jdt.annotation.NonNull
+org.eclipse.jdt.core.compiler.annotation.nonnull.secondary=
+org.eclipse.jdt.core.compiler.annotation.nonnullbydefault=org.eclipse.jdt.annotation.NonNullByDefault
+org.eclipse.jdt.core.compiler.annotation.nonnullbydefault.secondary=
+org.eclipse.jdt.core.compiler.annotation.nullable=org.eclipse.jdt.annotation.Nullable
+org.eclipse.jdt.core.compiler.annotation.nullable.secondary=
+org.eclipse.jdt.core.compiler.annotation.nullanalysis=enabled
+org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
+org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.8
+org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
+org.eclipse.jdt.core.compiler.compliance=1.8
+org.eclipse.jdt.core.compiler.debug.lineNumber=generate
+org.eclipse.jdt.core.compiler.debug.localVariable=generate
+org.eclipse.jdt.core.compiler.debug.sourceFile=generate
+org.eclipse.jdt.core.compiler.problem.APILeak=warning
+org.eclipse.jdt.core.compiler.problem.annotatedTypeArgumentToUnannotated=info
+org.eclipse.jdt.core.compiler.problem.annotationSuperInterface=warning
+org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
+org.eclipse.jdt.core.compiler.problem.autoboxing=ignore
+org.eclipse.jdt.core.compiler.problem.comparingIdentical=warning
+org.eclipse.jdt.core.compiler.problem.deadCode=warning
+org.eclipse.jdt.core.compiler.problem.deprecation=warning
+org.eclipse.jdt.core.compiler.problem.deprecationInDeprecatedCode=disabled
+org.eclipse.jdt.core.compiler.problem.deprecationWhenOverridingDeprecatedMethod=disabled
+org.eclipse.jdt.core.compiler.problem.discouragedReference=warning
+org.eclipse.jdt.core.compiler.problem.emptyStatement=ignore
+org.eclipse.jdt.core.compiler.problem.enablePreviewFeatures=disabled
+org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
+org.eclipse.jdt.core.compiler.problem.explicitlyClosedAutoCloseable=ignore
+org.eclipse.jdt.core.compiler.problem.fallthroughCase=ignore
+org.eclipse.jdt.core.compiler.problem.fatalOptionalError=disabled
+org.eclipse.jdt.core.compiler.problem.fieldHiding=ignore
+org.eclipse.jdt.core.compiler.problem.finalParameterBound=warning
+org.eclipse.jdt.core.compiler.problem.finallyBlockNotCompletingNormally=warning
+org.eclipse.jdt.core.compiler.problem.forbiddenReference=error
+org.eclipse.jdt.core.compiler.problem.hiddenCatchBlock=warning
+org.eclipse.jdt.core.compiler.problem.includeNullInfoFromAsserts=disabled
+org.eclipse.jdt.core.compiler.problem.incompatibleNonInheritedInterfaceMethod=warning
+org.eclipse.jdt.core.compiler.problem.incompleteEnumSwitch=warning
+org.eclipse.jdt.core.compiler.problem.indirectStaticAccess=ignore
+org.eclipse.jdt.core.compiler.problem.localVariableHiding=ignore
+org.eclipse.jdt.core.compiler.problem.methodWithConstructorName=warning
+org.eclipse.jdt.core.compiler.problem.missingDefaultCase=ignore
+org.eclipse.jdt.core.compiler.problem.missingDeprecatedAnnotation=ignore
+org.eclipse.jdt.core.compiler.problem.missingEnumCaseDespiteDefault=disabled
+org.eclipse.jdt.core.compiler.problem.missingHashCodeMethod=ignore
+org.eclipse.jdt.core.compiler.problem.missingOverrideAnnotation=ignore
+org.eclipse.jdt.core.compiler.problem.missingOverrideAnnotationForInterfaceMethodImplementation=enabled
+org.eclipse.jdt.core.compiler.problem.missingSerialVersion=warning
+org.eclipse.jdt.core.compiler.problem.missingSynchronizedOnInheritedMethod=ignore
+org.eclipse.jdt.core.compiler.problem.noEffectAssignment=warning
+org.eclipse.jdt.core.compiler.problem.noImplicitStringConversion=warning
+org.eclipse.jdt.core.compiler.problem.nonExternalizedStringLiteral=ignore
+org.eclipse.jdt.core.compiler.problem.nonnullParameterAnnotationDropped=warning
+org.eclipse.jdt.core.compiler.problem.nonnullTypeVariableFromLegacyInvocation=warning
+org.eclipse.jdt.core.compiler.problem.nullAnnotationInferenceConflict=error
+org.eclipse.jdt.core.compiler.problem.nullReference=error
+org.eclipse.jdt.core.compiler.problem.nullSpecViolation=error
+org.eclipse.jdt.core.compiler.problem.nullUncheckedConversion=warning
+org.eclipse.jdt.core.compiler.problem.overridingPackageDefaultMethod=warning
+org.eclipse.jdt.core.compiler.problem.parameterAssignment=ignore
+org.eclipse.jdt.core.compiler.problem.pessimisticNullAnalysisForFreeTypeVariables=warning
+org.eclipse.jdt.core.compiler.problem.possibleAccidentalBooleanAssignment=ignore
+org.eclipse.jdt.core.compiler.problem.potentialNullReference=error
+org.eclipse.jdt.core.compiler.problem.potentiallyUnclosedCloseable=ignore
+org.eclipse.jdt.core.compiler.problem.rawTypeReference=warning
+org.eclipse.jdt.core.compiler.problem.redundantNullAnnotation=warning
+org.eclipse.jdt.core.compiler.problem.redundantNullCheck=ignore
+org.eclipse.jdt.core.compiler.problem.redundantSpecificationOfTypeArguments=ignore
+org.eclipse.jdt.core.compiler.problem.redundantSuperinterface=ignore
+org.eclipse.jdt.core.compiler.problem.reportMethodCanBePotentiallyStatic=ignore
+org.eclipse.jdt.core.compiler.problem.reportMethodCanBeStatic=ignore
+org.eclipse.jdt.core.compiler.problem.reportPreviewFeatures=warning
+org.eclipse.jdt.core.compiler.problem.specialParameterHidingField=disabled
+org.eclipse.jdt.core.compiler.problem.staticAccessReceiver=warning
+org.eclipse.jdt.core.compiler.problem.suppressOptionalErrors=disabled
+org.eclipse.jdt.core.compiler.problem.suppressWarnings=enabled
+org.eclipse.jdt.core.compiler.problem.suppressWarningsNotFullyAnalysed=info
+org.eclipse.jdt.core.compiler.problem.syntacticNullAnalysisForFields=disabled
+org.eclipse.jdt.core.compiler.problem.syntheticAccessEmulation=ignore
+org.eclipse.jdt.core.compiler.problem.terminalDeprecation=warning
+org.eclipse.jdt.core.compiler.problem.typeParameterHiding=warning
+org.eclipse.jdt.core.compiler.problem.unavoidableGenericTypeProblems=enabled
+org.eclipse.jdt.core.compiler.problem.uncheckedTypeOperation=warning
+org.eclipse.jdt.core.compiler.problem.unclosedCloseable=warning
+org.eclipse.jdt.core.compiler.problem.undocumentedEmptyBlock=ignore
+org.eclipse.jdt.core.compiler.problem.unhandledWarningToken=warning
+org.eclipse.jdt.core.compiler.problem.unlikelyCollectionMethodArgumentType=warning
+org.eclipse.jdt.core.compiler.problem.unlikelyCollectionMethodArgumentTypeStrict=disabled
+org.eclipse.jdt.core.compiler.problem.unlikelyEqualsArgumentType=info
+org.eclipse.jdt.core.compiler.problem.unnecessaryElse=ignore
+org.eclipse.jdt.core.compiler.problem.unnecessaryTypeCheck=ignore
+org.eclipse.jdt.core.compiler.problem.unqualifiedFieldAccess=ignore
+org.eclipse.jdt.core.compiler.problem.unstableAutoModuleName=warning
+org.eclipse.jdt.core.compiler.problem.unusedDeclaredThrownException=ignore
+org.eclipse.jdt.core.compiler.problem.unusedDeclaredThrownExceptionExemptExceptionAndThrowable=enabled
+org.eclipse.jdt.core.compiler.problem.unusedDeclaredThrownExceptionIncludeDocCommentReference=enabled
+org.eclipse.jdt.core.compiler.problem.unusedDeclaredThrownExceptionWhenOverriding=disabled
+org.eclipse.jdt.core.compiler.problem.unusedExceptionParameter=ignore
+org.eclipse.jdt.core.compiler.problem.unusedImport=warning
+org.eclipse.jdt.core.compiler.problem.unusedLabel=warning
+org.eclipse.jdt.core.compiler.problem.unusedLocal=warning
+org.eclipse.jdt.core.compiler.problem.unusedObjectAllocation=ignore
+org.eclipse.jdt.core.compiler.problem.unusedParameter=ignore
+org.eclipse.jdt.core.compiler.problem.unusedParameterIncludeDocCommentReference=enabled
+org.eclipse.jdt.core.compiler.problem.unusedParameterWhenImplementingAbstract=disabled
+org.eclipse.jdt.core.compiler.problem.unusedParameterWhenOverridingConcrete=disabled
+org.eclipse.jdt.core.compiler.problem.unusedPrivateMember=warning
+org.eclipse.jdt.core.compiler.problem.unusedTypeParameter=ignore
+org.eclipse.jdt.core.compiler.problem.unusedWarningToken=warning
+org.eclipse.jdt.core.compiler.problem.varargsArgumentNeedCast=warning
+org.eclipse.jdt.core.compiler.processAnnotations=disabled
+org.eclipse.jdt.core.compiler.release=disabled
+org.eclipse.jdt.core.compiler.source=1.8

org.eclipse.jdt.ls.tests/projects/eclipse/testnullable/src/org/sample/Main.java

@@ -0,0 +1,14 @@
+package org.sample;
+
+import java.util.ArrayList;
+
+public class Main {
+
+	public void test() {
+		String[] arr = (new ArrayList<>()).stream().toArray(String[]::new);
+		new Runnable() {
+			ru
+		}
+	}
+
+}

org.eclipse.jdt.ls.tests/src/org/eclipse/jdt/ls/core/internal/handlers/CompletionHandlerTest.java

@@ -34,6 +34,7 @@
 import java.util.Map;
 import java.util.stream.Collectors;
 
+import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.ResourcesPlugin;
 import org.eclipse.core.runtime.NullProgressMonitor;
@@ -49,6 +50,7 @@
 import org.eclipse.jdt.ls.core.internal.JavaClientConnection;
 import org.eclipse.jdt.ls.core.internal.JavaLanguageServerPlugin;
 import org.eclipse.jdt.ls.core.internal.JsonMessageHelper;
+import org.eclipse.jdt.ls.core.internal.ProjectUtils;
 import org.eclipse.jdt.ls.core.internal.TextEditUtil;
 import org.eclipse.jdt.ls.core.internal.WorkspaceHelper;
 import org.eclipse.jdt.ls.core.internal.contentassist.JavadocCompletionProposal;
@@ -3001,6 +3003,21 @@ public void testCompletion_javadocOriginal() throws JavaModelException {
 		assertEquals(" Test ", documentation);
 	}
 
+	@Test
+	public void testCompletion_Nullable() throws Exception {
+		importProjects("eclipse/testnullable");
+		IProject proj = ProjectUtils.getProject("testnullable");
+		assertTrue(ProjectUtils.isJavaProject(proj));
+		IFile file = proj.getFile("/src/org/sample/Main.java");
+		ICompilationUnit unit = JavaCore.createCompilationUnitFrom(file);
+		int[] loc = findCompletionLocation(unit, "ru");
+		CompletionList list = server.completion(JsonMessageHelper.getParams(createCompletionRequest(unit, loc[0], loc[1]))).join().getRight();
+		assertNotNull(list);
+		CompletionItem ci = list.getItems().stream().filter(item -> item.getLabel().equals("run() : void")).findFirst().orElse(null);
+		assertNotNull(ci);
+		assertEquals("public void run() {};", ci.getTextEdit().getNewText());
+	}
+
 	private String createCompletionRequest(ICompilationUnit unit, int line, int kar) {
 		return COMPLETION_TEMPLATE.replace("${file}", JDTUtils.toURI(unit))
 				.replace("${line}", String.valueOf(line))