cleanup: Remove unnecessary @SuppressWarnings

Change-Id: I1b239b587e1cc811bbd6e1513b07dc93a891a842
Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/AbbreviationTest.java

@@ -144,7 +144,6 @@ public class AbbreviationTest extends LocalDiskRepositoryTestCase {
 		assertEquals(id, db.resolve(reader.abbreviate(id, 8).name()));
 	}
 
-	@SuppressWarnings("unchecked")
 	public void testAbbreviateIsActuallyUnique() throws Exception {
 		// This test is far more difficult. We have to manually craft
 		// an input that contains collisions at a particular prefix,

org.eclipse.jgit/src/org/eclipse/jgit/storage/file/WindowCache.java

@@ -518,7 +518,6 @@ public class WindowCache {
 		gc();
 	}
 
-	@SuppressWarnings("unchecked")
 	private void gc() {
 		Ref r;
 		while ((r = (Ref) queue.poll()) != null) {