Why my Symbol reference is unidirectional (no usages)?

I’ve created TypeScript to Java Symbol reference which matches service calls by class and method names. It works perfectly TS → Java way, but then in Java file I see “No usages”

I’ve implemented:
NavigatableSymbol, PsiSymbolReference and PsiSymbolReferenceProvider

Our symbols implementation might be found here:

What should I do more to see usages of Java class methods?