@Test
public void shouldReturnTrueWhenThereIsKey() {

    ClassMapping classMapping = classConverter.create(User.class);
    List<FieldMapping> fields = classMapping.getFields();
    Predicate<FieldMapping> hasKeyAnnotation = FieldMapping::isId;
    assertTrue(fields.stream().anyMatch(hasKeyAnnotation));
    FieldMapping fieldMapping = fields.stream().filter(hasKeyAnnotation).findFirst().get();
    assertEquals("_id", fieldMapping.getName());
    assertEquals(DEFAULT, fieldMapping.getType());
}