private static boolean isUnreserved(int c) {
    return isAlpha(c) || isDigit(c) || c == '-' || c == '.' || c == '_' || c == '~';
  }
Percent Encode the provided byte.

@param data to encode
@param bos with the output stream to use.
core/src/main/java/feign/template/UriUtils.java