void (TypeMigrationUsageInfo usageInfo, PsiElement place) { if (place != null) { final Pair<TypeMigrationUsageInfo, TypeMigrationUsageInfo> rooted = Pair.create(usageInfo, myCurrentRoot); Set<PsiElement> usages = myRootUsagesTree.get(rooted); if (usages == null) { usages = new HashSet<>(); myRootUsagesTree.put(rooted, usages); } usages.add(place); } }