protected void enqueue(MethodCall<?> methodCall){
  if (!running.get()) {
    throw new IllegalStateException("Cannot write to a closed service client");
  }
  if (!pendingCalls.offer(methodCall)) {
    throw new IllegalStateException("Call queue is full");
  }
}

protected void enqueue ( MethodCall < ? > methodCall ) { if ( ! running . get ( ) ) { throw new IllegalStateException ( "Cannot write to a closed service client" ) ; } if ( ! pendingCalls . offer ( methodCall ) ) { throw new IllegalStateException ( "Call queue is full" ) ; } }
when invoked by a derived instance , places the given call in a queue to be sent to the server .
