static String encodeHex(byte[] bytes) {
		final char[] hex = new char[bytes.length * 2];

		int i = 0;
		for (byte b : bytes) {
			hex[i++] = HEX_DIGITS[(b >> 4) & 0x0f];
			hex[i++] = HEX_DIGITS[b & 0x0f];
		}

		return String.valueOf(hex);
	}
@Test
	public void encodeHex_Null_Failure() throws Exception {
		try {
			PubkeyUtils.encodeHex(null);
			fail("Should throw null pointer exception when argument is null");
		} catch (NullPointerException e) {
			// success
		}
	}