### Question:
HexUtils { public static String toHex(byte[] bytes) { return toHex(bytes, null); }  static String toHex(byte[] bytes); static String toHex(byte[] bytes, String separator); static String toHex(byte[] bytes, int offset, int length); static String toHex(byte b); static String toHex(byte[] bytes, int offset, int length, String separator); static byte[] toBytes(String hexString); static void appendByteAsHex(StringBuilder sb, byte b); static boolean isAllZero(byte[] bytes);  }### Answer:
@Test public void toHex() throws Exception { for(byte[] bytes : bytess) { String hex = new String(Hex.encode(bytes)); assertEquals(hex, HexUtils.toHex(bytes)); } }