JDK 9 RFR of JDK-8046271: Fix overrides lint warnings in Apple laf code

[Joe Darcy]

Hello,

One of the classes in the Apple laf code commits the classic mistake of 
override equals without also overriding hashCode. Please review my 
addition of a hashCode method:

diff -r 717cad3f30fe 
src/macosx/classes/com/apple/laf/AquaFileSystemModel.java
--- a/src/macosx/classes/com/apple/laf/AquaFileSystemModel.java Thu Jun 
05 23:17:05 2014 -0700
+++ b/src/macosx/classes/com/apple/laf/AquaFileSystemModel.java Fri Jun 
06 16:41:20 2014 -0700
@@ -365,8 +365,13 @@
         public boolean equals(final Object other) {
             final SortableFile otherFile = (SortableFile)other;
             return otherFile.fFile.equals(fFile);
         }
+
+        @Override
+        public int hashCode() {
+            return Objects.hashCode(fFile);
+        }
     }

     class LoadFilesThread extends Thread {
         Vector<Runnable> queuedTasks = new Vector<Runnable>();

Since the equals function is based on the fFile field, I made the 
hashCode based on that field as well. If fFile happens to be null (there 
is no null-check in the constructor), Objects.hashCode will return 0; 
otherwise, the hash of fFile will be returned.

Thanks,

-Joe