Check Gradle compatibility when importing fails

org.eclipse.jdt.ls.core/plugin.xml

@@ -100,6 +100,9 @@
             <command
                   id="java.navigate.resolveTypeHierarchy">
             </command>
+            <command
+                  id="java.project.upgradeGradle">
+            </command>
       </delegateCommandHandler>
    </extension>
    <extension
@@ -167,7 +170,7 @@
    </extension>
    <extension id="org.eclipse.jdt.ls.filesystem" name="JDT LS File System" point="org.eclipse.core.filesystem.filesystems">
       <filesystem scheme="file">
-         <run class="org.eclipse.jdt.ls.core.internal.filesystem.JLSFileSystem"/> 
+         <run class="org.eclipse.jdt.ls.core.internal.filesystem.JLSFileSystem"/>
       </filesystem>
    </extension>
 </plugin>

org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/EventType.java

@@ -19,18 +19,23 @@ public enum EventType {
 	 * classpath updated event.
 	 */
 	ClasspathUpdated(100),
-	
+
 	/**
 	 * projects imported event.
 	 */
-	ProjectsImported(200);
-
+	ProjectsImported(200),
+
+	/**
+	 * Incompatible issue between Gradle and Jdk event.
+	 */
+	IncompatibleGradleJdkIssue(300);
+
 	private final int value;
-	
+
 	EventType(int value) {
 		this.value = value;
 	}
-	
+
 	public int getValue() {
 		return value;
 	}

org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/JDTDelegateCommandHandler.java

@@ -25,6 +25,7 @@
 import org.eclipse.jdt.ls.core.internal.commands.ProjectCommand.ClasspathOptions;
 import org.eclipse.jdt.ls.core.internal.handlers.FormatterHandler;
 import org.eclipse.jdt.ls.core.internal.handlers.ResolveSourceMappingHandler;
+import org.eclipse.jdt.ls.core.internal.managers.GradleProjectImporter;
 import org.eclipse.jdt.ls.core.internal.commands.SourceAttachmentCommand;
 import org.eclipse.jdt.ls.core.internal.commands.TypeHierarchyCommand;
 import org.eclipse.lsp4j.ResolveTypeHierarchyItemParams;
@@ -114,6 +115,9 @@ public Object executeCommand(String commandId, List<Object> arguments, IProgress
 					params.setPosition(textParams.getPosition());
 					TypeHierarchyItem typeHierarchyItem = typeHierarchyCommand.typeHierarchy(params, monitor);
 					return typeHierarchyItem;
+				case "java.project.upgradeGradle":
+					String projectDir = (String) arguments.get(0);
+					return GradleProjectImporter.upgradeGradleVersion(projectDir, monitor);
 				default:
 					break;
 			}

org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/managers/GradleCompatibilityChecker.java

@@ -0,0 +1,60 @@
+/*******************************************************************************
+ * Copyright (c) 2018-2021 Microsoft Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Microsoft Corporation - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.jdt.ls.core.internal.managers;
+
+import org.eclipse.buildship.core.internal.util.gradle.GradleVersion;
+import org.eclipse.jdt.core.JavaCore;
+
+public class GradleCompatibilityChecker {
+
+	public static String MAX_SUPPORTED_JAVA = JavaCore.VERSION_17;
+	public static String CURRENT_GRADLE = "7.3.1";
+
+	public static boolean compatibilityCheck(GradleVersion gradleVersion, String javaVersion) {
+		if (gradleVersion == null || javaVersion == null || javaVersion.isEmpty()) {
+			return false;
+		}
+		String highestSupportedJava = getHighestSupportedJava(gradleVersion);
+		return JavaCore.compareJavaVersions(javaVersion, highestSupportedJava) > 0;
+	}
+
+	public static String getHighestSupportedJava(GradleVersion gradleVersion) {
+		GradleVersion baseVersion = gradleVersion.getBaseVersion();
+		try {
+			// https://docs.gradle.org/current/userguide/compatibility.html
+			if (baseVersion.compareTo(GradleVersion.version("7.3")) >= 0) {
+				return JavaCore.VERSION_17;
+			} else if (baseVersion.compareTo(GradleVersion.version("7.0")) >= 0) {
+				return JavaCore.VERSION_16;
+			} else if (baseVersion.compareTo(GradleVersion.version("6.7")) >= 0) {
+				return JavaCore.VERSION_15;
+			} else if (baseVersion.compareTo(GradleVersion.version("6.3")) >= 0) {
+				return JavaCore.VERSION_14;
+			} else if (baseVersion.compareTo(GradleVersion.version("6.0")) >= 0) {
+				return JavaCore.VERSION_13;
+			} else if (baseVersion.compareTo(GradleVersion.version("5.4")) >= 0) {
+				return JavaCore.VERSION_12;
+			} else if (baseVersion.compareTo(GradleVersion.version("5.0")) >= 0) {
+				return JavaCore.VERSION_11;
+			} else if (baseVersion.compareTo(GradleVersion.version("4.7")) >= 0) {
+				return JavaCore.VERSION_10;
+			} else if (baseVersion.compareTo(GradleVersion.version("4.3")) >= 0) {
+				return JavaCore.VERSION_9;
+			}
+			return JavaCore.VERSION_1_8;
+		} catch (IllegalArgumentException e) {
+			return MAX_SUPPORTED_JAVA;
+		}
+	}
+
+}

org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/managers/GradleCompatibilityErrorMarker.java

@@ -0,0 +1,36 @@
+/*******************************************************************************
+ * Copyright (c) 2021 Microsoft Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Microsoft Corporation - initial API and implementation
+*******************************************************************************/
+package org.eclipse.jdt.ls.core.internal.managers;
+
+import org.eclipse.core.resources.IMarker;
+import org.eclipse.core.resources.IResource;
+import org.eclipse.core.runtime.CoreException;
+import org.eclipse.core.runtime.IStatus;
+import org.eclipse.core.runtime.MultiStatus;
+import org.eclipse.jdt.ls.core.internal.IConstants;
+import org.eclipse.jdt.ls.core.internal.managers.GradleProjectImporter.GradleCompatibilityStatus;
+
+public class GradleCompatibilityErrorMarker {
+	public static final String ID = IConstants.PLUGIN_ID + ".gradlecompatibilityerrormarker";
+
+	public static void createMarker(IResource resource, GradleCompatibilityStatus status) {
+		try {
+			IMarker marker = resource.createMarker(GradleCompatibilityErrorMarker.ID);
+			marker.setAttribute(IMarker.LINE_NUMBER, 1);
+			marker.setAttribute(IMarker.MESSAGE, status.getMessage());
+			marker.setAttribute(IMarker.SEVERITY, IMarker.SEVERITY_ERROR);
+		} catch (CoreException e) {
+			// do nothing
+		}
+	}
+}