code: public static void verifyParameterPresence(String parameterName, String parameter) {
      verifyParameterPresence(parameterName, (Object) parameter);
      if (parameter.trim().length() == 0) {
        throw new IllegalArgumentException("The '" + parameterName + "' parameter cannot be an empty string.");
      }
    }
docs: Ensures that {@code parameter} isn't {@code null} or an empty string.
  
  @param parameterName
  The name of the parameter (to be used in exception message).
  @param parameter
  The parameter to check.
  @throws IllegalArgumentException
  If {@code parameter} is {@code null} or an empty string.