code: @Nullable
      private static String concat(@Nullable String[] values, @NonNull String delimeter) {
          if (values == null || values.length == 0) {
              return null;
          }
          final StringBuilder str = new StringBuilder();
          for (String val : values) {
              str.append(val).append(delimeter);
          }
          str.delete(str.length() - delimeter.length(), str.length());
          return str.toString();
      }
docs: /* Helper methods