@Test
public void acceptNonJsonObjectString() {

    final String invalidJsonObjectString = "foo";
    final JsonObjectValueValidator underTest = JsonObjectValueValidator.getInstance();
    assertThatExceptionOfType(DittoHeaderInvalidException.class)
            .isThrownBy(() -> underTest.accept(DittoHeaderDefinition.AUTHORIZATION_CONTEXT, invalidJsonObjectString))
            .withMessageContaining(invalidJsonObjectString)
            .withMessageEndingWith("is not a valid JSON object.")
            .withNoCause();
}