Remove unnecessary boxing SuppressWarnings annotation

Change-Id: Id8a6d9f96860742f9094efdb4f31a952be7d3025

org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCacheEntry.java

@@ -562,7 +562,6 @@ public class DirCacheEntry {
 	 * @param sz
 	 *            new cached size of the file, as bytes.
 	 */
-	@SuppressWarnings("boxing")
 	public void setLength(final long sz) {
 		setLength((int) sz);
 	}