A DESCRIPTION OF THE REQUEST :
Java 1.7.0_09 doesn't support UserDefinedFileAttributeView.class on Mac OS 10.8.2. Thus Files.getFileAttributeView(VALID_PATH, UserDefinedFileAttributeView.class) always return null.

Mac by default uses HFS+. HFS+ supports extended attributes. In my test environment, extended attribute support is proved with the following scripts:

$ xattr -p hello test.txt
xattr: test.txt: No such xattr: hello
$ xattr -w hello world test.txt
$ xattr -p hello test.txt
world

Reference: http://en.m.wikipedia.org/wiki/HFS_Plus

Information of my system:

uname -a
Darwin MY_HOST_NAME 12.2.0 Darwin Kernel Version 12.2.0: Sat Aug 25 00:48:52 PDT 2012; root:xnu-2050.18.24~1/RELEASE_X86_64 x86_64

java -version
java version " 1.7.0_09 "
Java(TM) SE Runtime Environment (build 1.7.0_09-b05)
Java HotSpot(TM) 64-Bit Server VM (build 23.5-b02, mixed mode)
$ diskutil list
/dev/disk0
   #: TYPE NAME SIZE IDENTIFIER
   0: GUID_partition_scheme *251.0 GB disk0
   1: EFI 209.7 MB disk0s1
   2: Apple_HFS Macintosh HD 210.0 GB disk0s2
   3: Apple_Boot Recovery HD 650.0 MB disk0s3
   4: Microsoft Basic Data Win7 40.1 GB disk0s4
$ diskutil info disk0s2
   Device Identifier: disk0s2
   Device Node: /dev/disk0s2
   Part of Whole: disk0
   Device / Media Name: Customer

   Volume Name: Macintosh HD
   Escaped with Unicode: Macintosh%FF%FE%20%00HD

   Mounted: Yes
   Mount Point: /
   Escaped with Unicode: /

   File System Personality: Journaled HFS+
   Type (Bundle): hfs
   Name (User Visible): Mac OS Extended (Journaled)
   Journal: Journal size 24576 KB at offset 0x11502000
   Owners: Enabled

   Partition Type: Apple_HFS




JUSTIFICATION :
Java is supposed to be portable. There is no reason for the missing extended attributes support on Mac, given that Mac is one of the most popular OS.

Mac is a popular development platform for programs finally deployed to Linux/Windows/Solaris. The feature mismatch causes problem.

There are also a lot of Java application for Mac. They can't utilitize extended attribute that is an important file system feature.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Files.getFileStore(Paths.get( " ./ " )).supportsFileAttributeView(UserDefinedFileAttributeView.class) should return true.

 Files.getFileAttributeView(Paths.get( " / " ), UserDefinedFileAttributeView.class) return a valid, non-null UserDefinedFileAttributeView instance.
ACTUAL -
Files.getFileStore(Paths.get( " ./ " )).supportsFileAttributeView(UserDefinedFileAttributeView.class) should return *false*.

Files.getFileAttributeView(Paths.get( " / " ), UserDefinedFileAttributeView.class) return *null*.

---------- BEGIN SOURCE ----------
/**
 * it is tested to run as root
 */
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.attribute.UserDefinedFileAttributeView;

public class ExtFileAttributeChecker {

    public static void main(String[] args) throws IOException {
        System.out.println(Files.getFileStore(Paths.get( " ./ " )).supportsFileAttributeView(UserDefinedFileAttributeView.class));
    }
}
---------- END SOURCE ----------