code: private KieServerHttpRequest openOutput() throws IOException {
          if( output != null ) {
              return this;
          }
          getConnection().setDoOutput(true);
          final String charset = getHeaderParam(getConnection().getRequestProperty(CONTENT_TYPE), PARAM_CHARSET);
          output = new RequestOutputStream(getConnection().getOutputStream(), charset, bufferSize);
          return this;
      }
docs: Open output stream
  
  @return this request
  @throws IOException