@Test
public void hexStringToByteArrayShouldReturnCorrectByteArray() {

    assertThat(Strings.hexStringToByteArray(null)).isNull();
    assertThat(Strings.hexStringToByteArray("00")).isEqualTo(new byte[]{ 0 });
    assertThat(Strings.hexStringToByteArray("010203")).isEqualTo(new byte[]{ 1, 2, 3 });
    assertThat(Strings.hexStringToByteArray("CAFEBABE")).isEqualTo(new byte[]{ -54, -2, -70, -66 });
}