code: private static Identifier convert(final Identifier identifier) {
      	if (identifier == null || StringUtils.isBlank(identifier.getText())) {
              return identifier;
          } else {
          	return Identifier.toIdentifier(identifier.getText().replaceAll(REG_EXPR, REPLACEMENT_PATTERN).toLowerCase(Locale.ENGLISH));
          }
      }
docs: Convert.
  
  @param identifier
  the identifier
  @return the identifier