void (final VirtualFile file) { ++ fileCount; if (sameExtensionCase) { final String extension = file.getExtension(); if (extension == null) { sameExtensionCase = false; } else if (commonExtension == null) { commonExtension = extension; } else { sameExtensionCase &= commonExtension.equals(extension); } } final VirtualFile parentVirtualFile = file.getParent(); if (parentVirtualFile != null) { Set<String> namesList = folders.get(parentVirtualFile); if (namesList == null) { namesList = new HashSet<>(); folders.put(parentVirtualFile, namesList); } namesList.add(file.getName()); } }