code: boolean hasOutput() {
          if (pending == null) {
              return false;
          }
  
          if (pending.isEmpty()) {
              return false;
          }
  
          if (!pending.get(0).hasRemaining()) {
              return false;
          }
          return true;
      }
docs: Determines whether this connection has pending responses to be sent
  
  @return true  there are pending responses