Set<PsiFile> (PsiPackage pack, PsiPackage depPack) { Set<PsiFile> psiFiles = new HashSet<>(); final Map<PsiPackage, Set<PsiFile>> map = myFilesInDependentPackages.get(pack); if (map != null){ psiFiles = map.get(depPack); } if (psiFiles == null) { psiFiles = new HashSet<>(); } return psiFiles; }