docs: public Optional<String> parseSelectItemAlias() {
          if (lexerEngine.skipIfEqual(DefaultKeyword.AS)) {
              return parseWithAs(null, false, null);
          }
          if (lexerEngine.equalAny(getDefaultAvailableKeywordsForSelectItemAlias()) || lexerEngine.equalAny(getCustomizedAvailableKeywordsForSelectItemAlias())) {
              return parseAlias(null, false, null);
          }
          return Optional.absent();
      }