public interface PreparedFolders<T> {
    T preparation();
}

T preparation() - returns prepared data for subsequent tree building.

PreparedFoldersMapFile - Prepares folders as Map<String, Folder<File>>, where key is full folder name, 
and value is the folder with files.

PreparedFoldersMapFilesRaw - Prepares folders as Map<String, List<File>>, where key is full folder name, 
and value is the list of folder files.

PreparedFoldersMapFileSystem - Prepares folders as Map<String, Folder<File>>, where key is full folder name, 
and value is the folder with files.

PreparedFoldersMapFileWin - Prepares folders as Map<String, Folder<File>>, where key is full folder name, 
and value is the folder with files of Windows.

PreparedFoldersMapFile - Prepares folders as Map<String, Folder<File>>, where key is full folder name, 
and value is the folder with files.

PreparedFoldersMapRaw - Prepares raw data to map [key, value]: [folder name, list of files of this folder].

PreparedFoldersMapText - Prepares raw data to map [key, value]: [folder name, instance of Folder with list 
of files of this folder].

PreparedFolders prepares raw files for the subsequent tree folder building. This is the first point of building a tree folder.