### Question:
FailedItemMarshaller implements BytesWriter<ItemSource>, BytesReader<ItemSource>,
        ReadResolvable<FailedItemMarshaller> { public ObjectMapper objectMapper() { return objectMapper.copy(); } FailedItemMarshaller(); ObjectMapper objectMapper(); @Override void writeMarshallable(@NotNull WireOut wire); @Override void readMarshallable(@NotNull WireIn wire); @Override FailedItemMarshaller readResolve(); @Override ItemSource read(Bytes in, @Nullable ItemSource using); @Override void write(Bytes out, @NotNull ItemSource toWrite);  }### Answer:
@Test public void returnedObjectMapperIsACopyOfInternalMapper() { ObjectMapper configuredObjectMapper = new ObjectMapper(); FailedItemMarshaller failedItemMarshaller = new FailedItemMarshaller() { @Override ObjectMapper createConfiguredObjectMapper() { return configuredObjectMapper; } }; ObjectMapper result = failedItemMarshaller.objectMapper(); assertNotSame(configuredObjectMapper, result); }