Add missing @since tags for new API in ReceiveCommand

Change-Id: I6e5d29390b71a1c123bc90ec2e3435706ea9211c
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/transport/ReceiveCommand.java

@@ -505,7 +505,10 @@ public class ReceiveCommand {
 		return oldId;
 	}
 
-	/** @return expected old target for a symbolic reference. */
+	/**
+	 * @return expected old target for a symbolic reference.
+	 * @since 4.10
+	 */
 	@Nullable
 	public String getOldSymref() {
 		return oldSymref;
@@ -516,7 +519,10 @@ public class ReceiveCommand {
 		return newId;
 	}
 
-	/** @return requested new target for a symbolic reference. */
+	/**
+	 * @return requested new target for a symbolic reference.
+	 * @since 4.10
+	 */
 	@Nullable
 	public String getNewSymref() {
 		return newSymref;