code: public static ValidationResult validateVariableName(String identifier)
     {
        if (Strings.isNullOrEmpty(identifier))
           return new ValidationResult(ERROR, Messages.notNullOrEmpty(VARIABLE_NAME));
        return validateIdentifier(identifier, IdentifierType.VARIABLE_NAME);
     }
docs: Validates whether the <code>identifier</code> parameter is a valid variable name.
  
  @param identifier
  @return