code: @Override
      public ByteBuffer getByteBuffer() throws IOException {
          ByteBuf byteBuf = fileUpload.getByteBuf();
          try {
              return byteBuf.nioBuffer();
          } finally {
              byteBuf.release();
          }
      }
docs: Gets the content of this part as a <tt>ByteBuffer</tt>.
  
  <p>Because the contents of the file are released after being retrieved,
  this method can only be called <strong>once</strong></p>
  
  @return The content of this part as a <tt>ByteBuffer</tt>
  @throws IOException If an error occurs in retrieving the content