public static Charset detectCharsetFromMetaTag(@NotNull CharSequence content) {
    // check for <meta http-equiv="charset=CharsetName" > or <meta charset="CharsetName"> and return Charset
    // because we will lightly parse and explicit charset isn't used very often do quick check for applicability
    int charPrefix = StringUtil.indexOf(content, CHARSET);
    do {
      if (charPrefix == -1) return null;
      int charsetPrefixEnd = charPrefix + CHARSET.length();
      while (charsetPrefixEnd < content.length() && Character.isWhitespace(content.charAt(charsetPrefixEnd))) ++charsetPrefixEnd;
      if (charsetPrefixEnd < content.length() && content.charAt(charsetPrefixEnd) == '=') break;
      charPrefix = StringUtil.indexOf(content, CHARSET, charsetPrefixEnd);
    }
    while (true);

    if (content.length() > charPrefix + 200) {
      String name = tryFetchCharsetFromFileContent(content.subSequence(0, charPrefix + 200));
      if (name != null) {
        return CharsetToolkit.forName(name);
      }
    }
    String name = tryFetchCharsetFromFileContent(content);
    return CharsetToolkit.forName(name);
  }
public static Charset detectCharsetFromMetaTag(@NotNull CharSequence content)