code: private static boolean isLast(HttpMessage httpMessage) {
          if (httpMessage instanceof FullHttpMessage) {
              FullHttpMessage fullMessage = (FullHttpMessage) httpMessage;
              if (fullMessage.trailingHeaders().isEmpty() && !fullMessage.content().isReadable()) {
                  return true;
              }
          }
  
          return false;
      }
docs: Checks if the given HTTP message should be considered as a last SPDY frame.
  
  @param httpMessage check this HTTP message
  @return whether the given HTTP message should generate a <em>last</em> SPDY frame.