@Test
public void shouldReturnEmptyIfNoMediaTypeFoundInCache() throws Exception {

    final MediaType mediaType = new MediaType("application/vnd.example.add-recipe+json");
    when(schemaIdMappingCacheInitialiser.initialiseCache()).thenReturn(new HashMap<>());
    final Optional<String> schemaIdOptional = defaultSchemaIdMappingCache.schemaIdFor(mediaType);
    assertThat(schemaIdOptional.isPresent(), is(false));
}