docs: protected boolean hasContentLength() {
          boolean result = false;
          String contentLength = this.request.getHeader(RestMessageHeaders.CONTENT_LENGTH);
          if(contentLength != null) {
              try {
                  Long.parseLong(contentLength);
                  result = true;
              } catch(NumberFormatException nfe) {
                  logger.error("Exception when validating put request. Incorrect content length parameter. Cannot parse this to long: "
                                       + contentLength + ". Details: " + nfe.getMessage(),
                               nfe);
                  RestErrorHandler.writeErrorResponse(this.messageEvent,
                                                      HttpResponseStatus.BAD_REQUEST,
                                                      "Incorrect content length parameter. Cannot parse this to long: "
                                                              + contentLength + ". Details: "
                                                              + nfe.getMessage());
              }
          } else {
              logger.error("Error when validating put request. Missing Content-Length header.");
              RestErrorHandler.writeErrorResponse(this.messageEvent,
                                                  HttpResponseStatus.BAD_REQUEST,
                                                  "Missing Content-Length header");
          }
  
          return result;
      }