private static int replaceEscapePair(StringBuilder b, int midOffset, String replacement, int[] offsetToKeep) {
    b.replace(midOffset - 1, midOffset + 1, replacement);
    int shift = replacement.length() - 2;
    if (offsetToKeep[0] > midOffset) offsetToKeep[0] += shift;
    return midOffset + shift;
  }
private static int replaceEscapePair(StringBuilder b, int midOffset, String replacement, int[] offsetToKeep)