js_caption

    StringBuilder sb = new StringBuilder();
    Matcher matcher = Pattern.compile("(\")(.*?)(\"\s*:)").matcher(json);
    while (matcher.find()) {
      matcher.appendReplacement(sb, String.join("",
          matcher.group(1),
          matcher.group(2).substring(0, 1).toUpperCase(),
          matcher.group(2).substring(1),
          matcher.group(3))
      );
    }
    matcher.appendTail(sb);
    System.out.printf("%s\n", sb.toString());