private void invokeConnectFailureCallback(Exception e) {
   AsyncResult<Boolean> cb = connectCallback;
   connectCallback = nopAsyncBooleanResult;
   cb.onFailure(e);
   ;
 }
 private void invokeReadFailureCallback(Exception e) {
   AsyncResult<String> cb = readCallback;
   readCallback = nopAsyncStringResult;
   cb.onFailure(e);
 }
 private void invokeConnectSuccessfulCallback() {
   AsyncResult<Boolean> cb = connectCallback;
   connectCallback = nopAsyncBooleanResult;
   cb.onSuccess(true);
 }
 private void invokeReadSuccessfulCallback(String result) {
   AsyncResult<String> cb = readCallback;
   readCallback = nopAsyncStringResult;
   cb.onSuccess(result);
 }