@Test void enqueue_errorDoesntStopOtherCalls() {
    Exception e = new IllegalArgumentException();
    errorCallback(call1, e);
    successCallback(call2);

    Call<Void> call = AggregateCall.newVoidCall(List.of(call1, call2));

    call.enqueue(callback);

    verify(callback).onError(e);

    verify(call1).enqueue(any(Callback.class));
    verify(call2).enqueue(any(Callback.class));
    verifyNoMoreInteractions(call1, call2);
  }
This shows that regardless of success or error, we block on completion
zipkin/src/test/java/zipkin2/internal/AggregateCallTest.java