docs: protected int indexFirstOf(char[] s, char delim, int offset) {
          if (s == null || s.length == 0) {
              return -1;
          }
          // check boundaries
          if (offset < 0) {
              offset = 0;
          } else if (offset > s.length) {
              return -1;
          }
          for (int i = offset; i < s.length; i++) {
              if (s[i] == delim) {
                  return i;
              }
          }
          return -1;
      }