CauseItem[] (TrackingRunner runner, PsiExpression expression, MemoryStateChange history) { FactDefinition<DfaNullability> nullability = history.findFact(history.myTopOfStack, FactExtractor.nullability()); if (nullability.myFact == DfaNullability.NULLABLE || nullability.myFact == DfaNullability.NULL) { return new CauseItem[]{runner.findNullabilityCause(history, nullability.myFact)}; } return new CauseItem[0]; }