Fix boxing warnings

Change-Id: Idf4887a99e87c375ec32e2fd289cfce82d78cbce
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/reftable/ReftableTest.java

@@ -487,7 +487,7 @@ public class ReftableTest {
 	public void seekPastWithLotsOfRefs() throws IOException {
 		Ref[] refs = new Ref[500];
 		for (int i = 1; i <= 500; i++) {
-			refs[i - 1] = ref(String.format("refs/%d", i), i);
+			refs[i - 1] = ref(String.format("refs/%d", Integer.valueOf(i)), i);
 		}
 		ReftableReader t = read(write(refs));
 		try (RefCursor rc = t.allRefs()) {

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

@@ -370,7 +370,7 @@ public class FileReftableStack implements AutoCloseable {
 	private String filename(long low, long high) {
 		return String.format("%012x-%012x-%08x", //$NON-NLS-1$
 				Long.valueOf(low), Long.valueOf(high),
-				random.nextInt());
+				Integer.valueOf(random.nextInt()));
 	}
 
 	/**