Fix for dynamic registration of capabilities

lib/extension.ts

@@ -26,14 +26,6 @@ export async function activate(context: ExtensionContext) {
             // Synchronize the setting section 'java' to the server
             // NOTE: this currently doesn't do anything
             configurationSection: 'java',
-            // Notify the server about file changes to 'javaconfig.json' files contain in the workspace
-            fileEvents: [
-                workspace.createFileSystemWatcher('**/javaconfig.json'),
-                workspace.createFileSystemWatcher('**/pom.xml'),
-                workspace.createFileSystemWatcher('**/WORKSPACE'),
-                workspace.createFileSystemWatcher('**/BUILD'),
-                workspace.createFileSystemWatcher('**/*.java')
-            ]
         },
         outputChannelName: 'Java',
         revealOutputChannelOn: 4 // never

src/main/java/org/javacs/JavaLanguageServer.java

@@ -142,6 +142,7 @@ private Set<Path> docPath() {
         }
         return paths;
     }
+
     private Set<String> addExports() {
         if (!settings.has("addExports")) return Set.of();
         var array = settings.getAsJsonArray("addExports");
@@ -189,7 +190,7 @@ public InitializeResult initialize(InitializeParams params) {
     }
 
     private static final String[] watchFiles = {
-        "**/*.java", "**/pom.xml", "**/BUILD",
+        "**/*.java", "**/pom.xml", "**/BUILD", "**/javaconfig.json", "**/WORKSPACE"
     };
 
     @Override

src/main/java/org/javacs/lsp/LSP.java

@@ -6,6 +6,7 @@
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.util.Optional;
+import java.util.Random;
 import java.util.UUID;
 import java.util.concurrent.ArrayBlockingQueue;
 import java.util.concurrent.TimeUnit;
@@ -150,11 +151,20 @@ public void showMessage(ShowMessageParams params) {
         @Override
         public void registerCapability(String method, JsonElement options) {
             var params = new RegistrationParams();
-            params.id = UUID.randomUUID().toString();
-            params.method = method;
-            params.registerOptions = options;
-
-            notifyClient(send, "client/registerCapability", params);
+            var registration = new RegistrationParams.Registration();
+            registration.id = UUID.randomUUID().toString();
+            registration.method = method;
+            registration.registerOptions = options;
+            params.registrations.add(registration);
+            var jsonText = toJson(params);
+            var requestMethod = "client/registerCapability";
+            // The request should contain the id param. Otherwise, it will be considered a notification.
+            var id = new Random().nextInt();
+            var messageText =
+                    String.format(
+                            "{\"jsonrpc\":\"2.0\",\"id\":\"%d\",\"method\":\"%s\",\"params\":%s}",
+                            id, requestMethod, jsonText);
+            writeClient(send, messageText);
         }
 
         @Override
@@ -172,7 +182,7 @@ public static void connect(
         // Read messages and process cancellations on a separate thread
         class MessageReader implements Runnable {
             void peek(Message message) {
-                if (message.method.equals("$/cancelRequest")) {
+                if ("$/cancelRequest".equals(message.method)) {
                     var params = gson.fromJson(message.params, CancelParams.class);
                     var removed = pending.removeIf(r -> r.id != null && r.id.equals(params.id));
                     if (removed) LOG.info(String.format("Cancelled request %d, which had not yet started", params.id));

src/main/java/org/javacs/lsp/RegistrationParams.java

@@ -1,8 +1,14 @@
 package org.javacs.lsp;
 
 import com.google.gson.JsonElement;
+import java.util.ArrayList;
+import java.util.List;
 
 public class RegistrationParams {
-    public String id, method;
-    public JsonElement registerOptions;
+    List<Registration> registrations = new ArrayList<>();
+
+    public static class Registration {
+        public String id, method;
+        public JsonElement registerOptions;
+    }
 }