Unregister language server extension on LS shutdown

fix eclipse-lemminx#605

Signed-off-by: Andrew Obuchowicz <aobuchow@redhat.com>

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/XMLLanguageServer.java

@@ -43,12 +43,12 @@
 import org.eclipse.lsp4xml.services.IXMLDocumentProvider;
 import org.eclipse.lsp4xml.services.XMLLanguageService;
 import org.eclipse.lsp4xml.settings.AllXMLSettings;
-import org.eclipse.lsp4xml.settings.XMLCompletionSettings;
 import org.eclipse.lsp4xml.settings.InitializationOptionsSettings;
 import org.eclipse.lsp4xml.settings.LogsSettings;
 import org.eclipse.lsp4xml.settings.ServerSettings;
 import org.eclipse.lsp4xml.settings.SharedSettings;
 import org.eclipse.lsp4xml.settings.XMLCodeLensSettings;
+import org.eclipse.lsp4xml.settings.XMLCompletionSettings;
 import org.eclipse.lsp4xml.settings.XMLFormattingOptions;
 import org.eclipse.lsp4xml.settings.XMLGeneralClientSettings;
 import org.eclipse.lsp4xml.settings.XMLSymbolSettings;
@@ -176,6 +176,7 @@ public synchronized void updateSettings(Object initializationOptionsSettings) {
 
 	@Override
 	public CompletableFuture<Object> shutdown() {
+		xmlLanguageService.dispose();
 		return computeAsync(cc -> new Object());
 	}
 

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/services/extensions/XMLExtensionsRegistry.java

@@ -169,7 +169,7 @@ public void initializeIfNeeded() {
 	}
 
 	private synchronized void initialize() {
-		
+
 		if (initialized) {
 			return;
 		}
@@ -198,6 +198,16 @@ void unregisterExtension(IXMLExtension extension) {
 		extension.stop(this);
 	}
 
+	/**
+	 * Unregisters all registered extensions.
+	 */
+	public void dispose() {
+		// Copy the list of extensions to avoid ConcurrentModificationError
+		List<IXMLExtension> extensionReferences = new ArrayList<>();
+		extensions.forEach(extensionReferences::add);
+		extensionReferences.forEach(this::unregisterExtension);
+	}
+
 	public void registerCompletionParticipant(ICompletionParticipant completionParticipant) {
 		completionParticipants.add(completionParticipant);
 	}

org.eclipse.lsp4xml/src/test/java/org/eclipse/lsp4xml/services/extensions/ExtensionRegistryDisposeTest.java

@@ -0,0 +1,45 @@
+package org.eclipse.lsp4xml.services.extensions;
+
+import static org.junit.Assert.assertTrue;
+
+import org.eclipse.lsp4j.InitializeParams;
+import org.eclipse.lsp4xml.services.extensions.save.ISaveContext;
+import org.junit.Test;
+
+public class ExtensionRegistryDisposeTest {
+
+	@Test
+	public void testExtensionRegistryDipose() {
+		XMLExtensionsRegistry registry = new XMLExtensionsRegistry();
+		registry.initializeIfNeeded();
+		MockXMLExtension extension = new MockXMLExtension();
+		registry.registerExtension(extension);
+		assertTrue(!extension.isStopped());
+		registry.dispose();
+		assertTrue(extension.isStopped());
+		assertTrue(registry.getExtensions().isEmpty());
+	}
+}
+
+class MockXMLExtension implements IXMLExtension {
+	boolean stopped;
+
+	@Override
+	public void start(InitializeParams params, XMLExtensionsRegistry registry) {
+		stopped = false;
+	}
+
+	@Override
+	public void stop(XMLExtensionsRegistry registry) {
+		stopped = true;
+	}
+
+	@Override
+	public void doSave(ISaveContext context) {
+	}
+
+	public boolean isStopped() {
+		return stopped;
+	}
+
+}