Set<File> (@NotNull String path) { if (!mySourceMap.containsKey(path)) { SourceSet sourceSet = myArtifactsMap.myArtifactsMap.get(path); if (sourceSet != null) { Set<File> sources = sourceSet.getAllJava().getSrcDirs(); Set<File> calculatedSources = mySourceMap.putIfAbsent(path, sources); return calculatedSources != null ? calculatedSources : sources; } } return Collections.emptySet(); }