code: private boolean isValidReturnCode(String returnCode) {
  
          if (CmsStringUtil.isEmptyOrWhitespaceOnly(returnCode)) {
              return false;
          }
          int pos = returnCode.indexOf(":");
          if (pos > 0) {
              return CmsUUID.isValidUUID(returnCode.substring(0, pos))
                  && CmsUUID.isValidUUID(returnCode.substring(pos + 1));
          } else {
              return CmsUUID.isValidUUID(returnCode);
          }
      }
docs: Returns if the given return code is valid.<p>
  
  @param returnCode the return code to check
  
  @return <code>true</code> if the return code is valid