@Test
public void invalidEntityTagValue() {

    Mockito.when(headerDefinition.getJavaType()).thenReturn(EntityTag.class);
    final String value = "invalid\"foo\"";
    assertThatExceptionOfType(DittoHeaderInvalidException.class)
            .isThrownBy(() -> underTest.accept(headerDefinition, value))
            .withMessage("The value '%s' of the header '%s' is not a valid entity-tag.", value, HEADER_KEY)
            .withNoCause();
}