Correct @since tags for ObjectFilter

Although the stable-4.0 branch already exists, 4.0 development is
still happening on master until IP logs are sent for review, which
will happen at the end of May.

Change-Id: I863ba85c6303f8ef2eb13bca5e2d30e5d3c58b29
Signed-off-by: Jonathan Nieder <jrn@google.com>

org.eclipse.jgit/src/org/eclipse/jgit/revwalk/ObjectWalk.java

@@ -259,7 +259,7 @@ public class ObjectWalk extends RevWalk {
 	 *
 	 * @return the current filter. Never null as a filter is always needed.
 	 *
-	 * @since 4.1
+	 * @since 4.0
 	 */
 	public ObjectFilter getObjectFilter() {
 		return objectFilter;
@@ -279,7 +279,7 @@ public class ObjectWalk extends RevWalk {
 	 *            the new filter. If null the special {@link ObjectFilter#ALL}
 	 *            filter will be used instead, as it matches every object.
 	 *
-	 * @since 4.1
+	 * @since 4.0
 	 */
 	public void setObjectFilter(ObjectFilter newFilter) {
 		assertNotStarted();

org.eclipse.jgit/src/org/eclipse/jgit/revwalk/filter/ObjectFilter.java

@@ -57,7 +57,7 @@ import org.eclipse.jgit.revwalk.ObjectWalk;
  * Applications should install the filter on an ObjectWalk by
  * {@link ObjectWalk#setObjectFilter(ObjectFilter)} prior to starting traversal.
  *
- * @since 4.1
+ * @since 4.0
  */
 public abstract class ObjectFilter {
 	/** Default filter that always returns true. */