code: @Override
      public Builder issuer(String issuerUrl) throws InvalidClaimException {
          if (issuerUrl != null && !issuerUrl.isEmpty()) {
              claims.put(Claims.ISSUER, issuerUrl);
          } else {
              String err = Tr.formatMessage(tc, "JWT_INVALID_CLAIM_VALUE_ERR", new Object[] { Claims.ISSUER, issuerUrl });
              throw new InvalidClaimException(err);
          }
          return this;
      }
docs: /*
  (non-Javadoc)
  
  @see com.ibm.ws.security.jwt.internal.Builder#issuer(java.lang.String)