Micronaut: mixing @transaction with gRPC Endpoint methods

CreateProposalEndpoint.kt

@Singleton
open class CreateProposalEndpoint(@Inject val repository: ProposalRespository) : ProposalGrpcServiceGrpc.ProposalGrpcServiceImplBase() {

    @Transactional // starts the current transaction
    open override fun create(request: CreateProposalRequest, responseObserver: StreamObserver<CreateProposalResponse>) {

        val proposal = repository.save(request.toModel()) // with Hibernate, the INSERT may not be flushed here

        // returns to the client without waiting for the commit
        responseObserver.onNext(CreateProposalResponse.newBuilder().build())
        responseObserver.onCompleted()
      
    } // WARNING: the current transaction is only commited (and flushed) here
}

Micronaut Data Transactions with R2DBC