Simplify comparator code

Use lambda style comparators where possible. They are easier to read.

Change-Id: I5b80cfcd90909c94286742fa83af71015532809f
Signed-off-by: Michael Keppler <Michael.Keppler@gmx.de>

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackedBatchRefUpdate.java

@@ -366,12 +366,8 @@ class PackedBatchRefUpdate extends BatchRefUpdate {
 			List<ReceiveCommand> commands) throws IOException {
 		// Construct a new RefList by merging the old list with the updates.
 		// This assumes that each ref occurs at most once as a ReceiveCommand.
-		Collections.sort(commands, new Comparator<ReceiveCommand>() {
-			@Override
-			public int compare(ReceiveCommand a, ReceiveCommand b) {
-				return a.getRefName().compareTo(b.getRefName());
-			}
-		});
+		Collections.sort(commands,
+				Comparator.comparing(ReceiveCommand::getRefName));
 
 		int delta = 0;
 		for (ReceiveCommand c : commands) {