FileSystems { public static FileSystem getDefault() { return DefaultFileSystemHolder.defaultFileSystem; } private  FileSystems(); static FileSystem getDefault(); static FileSystem getFileSystem(final URI uri); static FileSystem newFileSystem(final URI uri,
                                           final Map<String, ?> env); static FileSystem newFileSystem(final Path path,
                                           final ClassLoader loader); static FileSystem newFileSystem(final URI uri,
                                           final Map<String, ?> env,
                                           final ClassLoader loader);  }
@Test public void testGetDefault() { assertThat(FileSystems.getDefault()) .isInstanceOf(BaseSimpleFileSystem.class); }