Flaky test fix

src/main/java/org/java_websocket/WebSocketImpl.java

@@ -78,6 +78,7 @@ public class WebSocketImpl implements WebSocket {
    */
   public static final int DEFAULT_PORT = 80;
 
+  private static volatile int executionCounter = 0;
   /**
    * The default wss port of WebSockets, as defined in the spec. If the nullary constructor is used,
    * DEFAULT_WSS_PORT will be the port the WebSocketServer is binded to. Note that ports under 1024
@@ -569,6 +570,11 @@ public synchronized void closeConnection(int code, String message, boolean remot
     }
     handshakerequest = null;
     readyState = ReadyState.CLOSED;
+    executionCounter += 1;
+  }
+
+  public static int getExecutionCounter() {
+    return executionCounter;
   }
 
   protected void closeConnection(int code, boolean remote) {

src/test/java/org/java_websocket/issues/Issue677Test.java

@@ -116,6 +116,9 @@ public void onStart() {
     assertTrue("webSocket.isOpen()", webSocket0.isOpen());
     webSocket0.close();
     countDownLatch0.await();
+    while (org.java_websocket.WebSocketImpl.getExecutionCounter() < 2) {
+      Thread.yield();
+    }
     assertTrue("webSocket.isClosed()", webSocket0.isClosed());
     webSocket1.connectBlocking();
     assertTrue("webSocket.isOpen()", webSocket1.isOpen());