code: public static void checkStringNotNullOrEmpty(String parameterName,
              String value) {
          if (TextUtils.isEmpty(value)) {
              throw Exceptions.IllegalArgument("Current input string %s is %s.",
                      parameterName, value == null ? "null" : "empty");
          }
      }
docs: Check that the parameter string is not null or empty
  
  @param value
  String value to be checked.
  @param parameterName
  The name of the user-supplied parameter that we are validating
  so that the user can easily find the error in their code.
  @throws IllegalArgumentException
  If the key is null or empty.