Add support for exiting immediately from a shutdown() request.

- In languageclient 7.x, the client fails to send the necessary exit()
  once a shutdown() response is received from the language server
- When client defines shouldLanguageServerExitOnShutdown as true, the
  language server will exit immediately after the shutdown request
- Adjust CHANGELOG for a 0.17.1 release

Signed-off-by: Roland Grunberg <rgrunber@redhat.com>

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Change Log
 
+## [0.17.1](https://github.com/eclipse/lemminx/milestone/25?closed=1) (June 25, 2021)
+
+### Bug Fixes
+
+ * Add support for exiting immediately from a shutdown() request. See [#1070](https://github.com/eclipse/lemminx/pull/1070).
+
 ## [0.17.0](https://github.com/eclipse/lemminx/milestone/23?closed=1) (June 22, 2021)
 
 ### Enhancements

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

@@ -226,6 +226,9 @@ private synchronized void updateSettings(Object initOptions, boolean initLogs) {
 	@Override
 	public CompletableFuture<Object> shutdown() {
 		xmlLanguageService.dispose();
+		if (capabilityManager.getClientCapabilities().getExtendedCapabilities().shouldLanguageServerExitOnShutdown()) {
+			delayer.schedule(() -> exit(0) , 1, TimeUnit.SECONDS);
+		}
 		return computeAsync(cc -> new Object());
 	}
 

org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/client/ExtendedClientCapabilities.java

@@ -26,6 +26,8 @@ public class ExtendedClientCapabilities {
 
 	private boolean openSettingsCommandSupport;
 
+	private boolean shouldLanguageServerExitOnShutdown;
+
 	public ExtendedCodeLensCapabilities getCodeLens() {
 		return codeLens;
 	}
@@ -75,4 +77,24 @@ public void setOpenSettingsCommandSupport(boolean openSettingsCommandSupport) {
 		this.openSettingsCommandSupport = openSettingsCommandSupport;
 	}
 
+	/**
+	 * Sets the boolean permitting language server to exit on client
+	 * shutdown() request, without waiting for client to call exit()
+	 *
+	 * @param shouldLanguageServerExitOnShutdown
+	 */
+	public void setShouldLanguageServerExitOnShutdown(boolean shouldLanguageServerExitOnShutdown) {
+		this.shouldLanguageServerExitOnShutdown = shouldLanguageServerExitOnShutdown;
+	}
+
+	/**
+	 * Returns true if the client should exit on shutdown() request and
+	 * avoid waiting for an exit() request
+	 *
+	 * @return true if the language server should exit on shutdown() request
+	 */
+	public boolean shouldLanguageServerExitOnShutdown() {
+		return shouldLanguageServerExitOnShutdown;
+	}
+
 }