### Question:
ConvertUtils { public static boolean isHexString(String input) { if (input == null) { return false; } if (0 != input.length() % 2) { return false; } try { getBytesInternal(input); return true; } catch (DecoderException e) { return false; } } private  ConvertUtils(); static byte[] getBytes(final String hexString); static String toHex(final byte[] bytes); static String padHex(final String hex, int hexStringSize); static byte[] fromHexToBytes(String hexString); static Pair<String, Integer> xorValues(String originalValue, String newValue); static String fromHexToString(final String hexString); static String fromStringToHex(final String plainText); static String toSize16Hex(final BigInteger number); static void validateNotNegative(final BigInteger number); static void validateNotNegative(final long number); static String toString(final BigInteger number); static BigInteger toUnsignedBigInteger(long value); static BigInteger toUnsignedBigInteger(BigInteger value); static boolean isHexString(String input); static void validateIsHexString(String input); static void validateIsHexString(String input, Integer size); static String reverseHexString(String hex); static byte[] xor(byte[] b1, byte[] b2);  }### Answer:
@Test void testIsHexString() { Assertions.assertTrue(ConvertUtils.isHexString("026ee415fc15")); Assertions.assertTrue(ConvertUtils.isHexString("abcdef0123456789ABCDEF")); Assertions.assertFalse(ConvertUtils.isHexString("abcdef012345G789ABCDEF")); Assertions.assertFalse(ConvertUtils.isHexString("026ee415fc1")); Assertions.assertFalse(ConvertUtils.isHexString(null)); }