Nested Interface-based projection fails with `ConverterNotFoundException`

[ELMORABITYounes]

Starting from spring-data-mongodb 3.4.3 (spring boot 2.7.4) when trying to use interface-based recusive projeection as described here, a ConverterNotFoundException is thrown (see example below).

You can find here a simple project for reproducing the issue.

Note that the issue is only reproducible when using reactive repositories and not when using blocking repositories.

Example:

java.lang.AssertionError: expectation "expectNextMatches" failed (expected: onNext(); actual: onError(org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [com.example.reactivemongoprojectionissue.bmodels.ApiSubTransaction] to type [com.example.reactivemongoprojectionissue.models.SubTransactionProjection]))
	at reactor.test.MessageFormatter.assertionError(MessageFormatter.java:115)
	at reactor.test.MessageFormatter.failPrefix(MessageFormatter.java:104)
	at reactor.test.MessageFormatter.fail(MessageFormatter.java:73)
	at reactor.test.MessageFormatter.failOptional(MessageFormatter.java:88)
	at reactor.test.DefaultStepVerifierBuilder.lambda$expectNextMatches$11(DefaultStepVerifierBuilder.java:556)
	at reactor.test.DefaultStepVerifierBuilder$SignalEvent.test(DefaultStepVerifierBuilder.java:2288)
	at reactor.test.DefaultStepVerifierBuilder$DefaultVerifySubscriber.onSignal(DefaultStepVerifierBuilder.java:1528)
	at reactor.test.DefaultStepVerifierBuilder$DefaultVerifySubscriber.onExpectation(DefaultStepVerifierBuilder.java:1476)
	at reactor.test.DefaultStepVerifierBuilder$DefaultVerifySubscriber.onError(DefaultStepVerifierBuilder.java:1129)
	at reactor.core.publisher.FluxUsingWhen$UsingWhenSubscriber.deferredError(FluxUsingWhen.java:398)
	at reactor.core.publisher.FluxUsingWhen$RollbackInner.onComplete(FluxUsingWhen.java:475)
	at reactor.core.publisher.Operators.complete(Operators.java:137)
	at reactor.core.publisher.MonoEmpty.subscribe(MonoEmpty.java:46)
	at reactor.core.publisher.Mono.subscribe(Mono.java:4455)
	at reactor.core.publisher.FluxUsingWhen$UsingWhenSubscriber.onError(FluxUsingWhen.java:364)
	at reactor.core.publisher.MonoFlatMapMany$FlatMapManyInner.onError(MonoFlatMapMany.java:255)
	at reactor.core.publisher.FluxMap$MapSubscriber.onError(FluxMap.java:134)
	at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:106)
	at reactor.core.publisher.Operators.error(Operators.java:198)
	at reactor.core.publisher.MonoError.subscribe(MonoError.java:53)
	at reactor.core.publisher.Mono.subscribe(Mono.java:4455)
	at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:103)
	at reactor.core.publisher.MonoFlatMapMany$FlatMapManyInner.onError(MonoFlatMapMany.java:255)
	at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.drain(FluxConcatMap.java:383)
	at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onNext(FluxConcatMap.java:251)
	at reactor.core.publisher.FluxCreate$BufferAsyncSink.drain(FluxCreate.java:814)
	at reactor.core.publisher.FluxCreate$BufferAsyncSink.next(FluxCreate.java:739)
	at reactor.core.publisher.FluxCreate$SerializedFluxSink.next(FluxCreate.java:161)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)

[christophstrobl]

@ELMORABITYounes thanks for reporting and the reproducer. We'll have a look.

[christophstrobl]

So there's a code snippet AbstractReactiveMongoQuery:L139-L141 that resets the type to read. However that one had been there even before 3.4.3 so it's likely the cause is another one.
Might be a side effect of 52886e1. But requires further investigation.

[christophstrobl]

confirmed - context resolution for the given property is breaking the interface projection for nested objects.