jdk/src/share/classes/sun/security/smartcardio/PCSC.java

    private final static char[] hexDigits = "0123456789abcdef".toCharArray();

    public static String toString(byte[] b) {
        StringBuffer sb = new StringBuffer(b.length * 3);
        for (int i = 0; i < b.length; i++) {
            int k = b[i] & 0xff;
            if (i != 0) {
                sb.append(':');
            }
            sb.append(hexDigits[k >>> 4]);
            sb.append(hexDigits[k & 0xf]);
        }
        return sb.toString();
    }


Can be replaced with

            sb.append(Integer.toHexString(k >>> 4));
            sb.append(Integer.toHexString(k & 0xf));