docs: public byte[] getRawData() throws IOException
      {
          int contentLength = request.getContentLength();
          if( contentLength<0 ) {
              return null;
          }
          
          byte[] buffer = new byte[contentLength];
          ServletInputStream is = request.getInputStream();
          for (int i = 0; i < contentLength; ) {
              int rLen = is.read(buffer, i, contentLength - i);
              if ( rLen == -1 ) {
                  break;
              }
              
              i += rLen;
          }
          
          return buffer;
      }