SubmoduleUpdateCommand: Add fetch callback

When the submodule already exists, it is fetched instead of
cloned.

Use the fetch callback instead of clone callback in this case.

Change-Id: I170c21ab92b4117f25fdf940fe6807f214b04d39
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

org.eclipse.jgit/src/org/eclipse/jgit/api/SubmoduleUpdateCommand.java

@@ -91,6 +91,8 @@ public class SubmoduleUpdateCommand extends
 
 	private CloneCommand.Callback callback;
 
+	private FetchCommand.Callback fetchCallback;
+
 	private boolean fetch = false;
 
 	/**
@@ -191,10 +193,8 @@ public class SubmoduleUpdateCommand extends
 						clone.setProgressMonitor(monitor);
 					submoduleRepo = clone.call().getRepository();
 				} else if (this.fetch) {
-					if (callback != null) {
-						// FIXME: Do we need a new callback to tell them we're
-						// fetching?
-						callback.cloningSubmodule(generator.getPath());
+					if (fetchCallback != null) {
+						fetchCallback.fetchingSubmodule(generator.getPath());
 					}
 					FetchCommand fetchCommand = Git.wrap(submoduleRepo).fetch();
 					if (monitor != null) {
@@ -274,4 +274,18 @@ public class SubmoduleUpdateCommand extends
 		this.callback = callback;
 		return this;
 	}
+
+	/**
+	 * Set status callback for submodule fetch operation.
+	 *
+	 * @param callback
+	 *            the callback
+	 * @return {@code this}
+	 * @since 4.9
+	 */
+	public SubmoduleUpdateCommand setFetchCallback(
+			FetchCommand.Callback callback) {
+		this.fetchCallback = callback;
+		return this;
+	}
 }