Unit testing nested subflows (subflows of subflows)

Question

I'm trying to write unit test for a flow, which has subflow, which, itself, has another subflow.

I register first flow using FlowDefinitionResource getResource(FlowDefinitionResourceFactory resourceFactory).

Then I register subflow definitions during test execution in FlowDefinitionRegistry before transitioning to them.

Transitioning to "first level" subflow goes ok. The result of transitioning to subflow of current subflow - NoSuchFlowDefinitionException.

The problem is that subflow definitions are all seem attached to the primary flow of the test and subflow can't be found within another subflow.

Is there any way to attach subflow definition to another subflow in tests, which extend AbstractXmlFlowExecutionTests?