@Test void delegatesSpanStore() {
    SpanStore spanStore = mock(SpanStore.class);
    when(delegate.spanStore()).thenReturn(spanStore);

    assertThat(forwarder.spanStore()).isEqualTo(spanStore);

    verify(delegate).spanStore();
  }
This test is intentionally brittle. It should break if we add new methods on {@link
StorageComponent}!
zipkin/src/test/java/zipkin2/storage/ForwardingStorageComponentTest.java