A string that uniquely identifies this file's location
A string that identifies the version of a file: If it equals the version of another file with the same absolute path, the two files must be equal.
A string that identifies the version of a file: If it equals the version of another file with the same absolute path, the two files must be equal. This is usually the lastModified date, but ordering is not required
List files in a directory
A string that globally identifies the version of a file: If it equals the global version of any other file, they must equal.
Abstraction of a FileSystem, so classpath builders can be used with virtual file systems