### Question:
PathUtils { public static byte[] base64Decode(String data) { byte[] d = Base64.getDecoder().decode(data.getBytes()); return d; }  static String computeFileContentHash(Path path); static String base64Encode(byte[] bytes); static byte[] base64Decode(String data); static boolean isFileHidden(Path file); static Path getCommonPath(Path path1, Path path2);  }### Answer:
@Test public void testBase64Decode() { String encoded = "aGVsbG8gd29ybGQ="; String expected = "hello world"; byte[] decoded = PathUtils.base64Decode(encoded); String content = new String(decoded); assertTrue(content.equals(expected)); }