docs: public final int toChars(int[] src, int srcOff, int srcLen, char[] dest, int destOff) {
      if (srcLen < 0) {
        throw new IllegalArgumentException("srcLen must be >= 0");
      }
      int written = 0;
      for (int i = 0; i < srcLen; ++i) {
        written += Character.toChars(src[srcOff + i], dest, destOff + written);
      }
      return written;
    }