@Override
    public Mono<ExtensionStore> create(String name, byte[] data) {
        return repository.save(new ExtensionStore(name, data))
            .onErrorMap(DuplicateKeyException.class,
                t -> new DuplicateNameException("Duplicate name detected.", t));
    }
@Test
    void create() {
        var expectedExtension =
            new ExtensionStore("/registry/posts/hello-halo", "hello halo".getBytes(), 2L);

        when(repository.save(any()))
            .thenReturn(Mono.just(expectedExtension));

        var createdExtension =
            client.create("/registry/posts/hello-halo", "hello halo".getBytes())
                .block();

        assertEquals(expectedExtension, createdExtension);
    }