code: @Override
      public byte[] asBytes() throws IOException {
          try (ServletInputStream stream = request.getInputStream()) {
              ByteArrayOutputStream array = new ByteArrayOutputStream(stream.available());
              return array.toByteArray();
          }
      }
docs: Reads entire request data as byte array. Do not use for large data sets to avoid
  memory issues.
  
  @return data sent by client as string.
  @throws IOException