public static byte[] decode(byte[] in) {
    return decode(in, in.length);
  }
copied from <a href=
"https://github.com/square/okhttp/blob/master/okhttp-protocols/src/main/java/com/squareup/okhttp/internal/Base64.java">okhttp</a>

@author Alexander Y. Kleymenov
core/src/main/java/feign/auth/Base64.java