code: protected String parseUserId(String securityName) {
          int idx = securityName.indexOf(TOKEN_DELIMETER); // Don't use String.split() - way too expensive.
          if (idx > 0) {
              return securityName.substring(0, idx);
          } else {
              return securityName;
          }
      }
docs: In case of SAF registry securityName returned will be of format <userId>::<token>.
  
  @return the userId