return replaceImpl(matcher, replaceStr, startIndex, endIndex, replaceCount);
int insertLen = (replaceStr == null ? 0 : replaceStr.length()); replaceImpl(startIndex, endIndex, endIndex - startIndex, replaceStr, insertLen); return this;
    public StrBuilder replace(            StrMatcher matcher, String replaceStr,            int startIndex, int endIndex, int replaceCount) {        endIndex = validateRange(startIndex, endIndex);        return replaceImpl(matcher, replaceStr, startIndex, endIndex, replaceCount);    }