Support pausing VM

src/main/java/org/javacs/debug/JavaDebugServer.java

@@ -433,6 +433,16 @@ public void disconnect(DisconnectArguments req) {
         vm = null;
     }
 
+    @Override
+    public void pause(PauseArguments req) {
+        LOG.info("Suspending threads");
+        vm.suspend();
+        var evt = new StoppedEventBody();
+        evt.reason = "suspended";
+        evt.allThreadsStopped = true;
+        client.stopped(evt);
+    }
+
     @Override
     public void terminate(TerminateArguments req) {
         vm.exit(1);

src/main/java/org/javacs/debug/proto/DebugAdapter.java

@@ -337,6 +337,12 @@ private void processRequest(JsonObject json) {
                         ack(req);
                         break;
                     }
+                case "pause":
+                    {
+                        server.pause(gson.fromJson(json, PauseRequest.class).arguments);
+                        ack(req);
+                        break;
+                    }
                 case "terminate":
                     {
                         server.terminate(gson.fromJson(json, TerminateRequest.class).arguments);

src/main/java/org/javacs/debug/proto/DebugServer.java

@@ -17,6 +17,8 @@ public interface DebugServer {
 
     void disconnect(DisconnectArguments req);
 
+    void pause(PauseArguments req);
+
     void terminate(TerminateArguments req);
 
     void continue_(ContinueArguments req);