RevWalk: Make createCommit(AnyObjectId, int) protected API

This allows sub-types of RevWalk to implement this method and create
instances of sub-types of RevCommit that know their position in the
Commit Graph.

Marked createCommit(AnyObjectId) as @nooverride

Existing sub-types of RevWalk within jgit have been updated to override
the new method. Sub-types of RevWalk outside of jgit will only receive a
warning, that the createCommit(AnyObjectId) method is no longer intended
to be overridden and that the new createCommit(AnyObjectId, int) method
should be overridden instead.

Bug: jgit-250
Change-Id: I0a2115bfef7e73a299780a2c28ef5a01aa1d00e0

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

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/NameRevCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/NameRevCommand.java
index 1ff6e98..f72a451 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/NameRevCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/NameRevCommand.java
@@ -96,7 +96,7 @@ protected NameRevCommand(Repository repo) {
 		revs = new ArrayList<>(2);
 		walk = new RevWalk(repo) {
 			@Override
-			public NameRevCommit createCommit(AnyObjectId id) {
+			protected RevCommit createCommit(AnyObjectId id, int graphPos) {
 				return new NameRevCommit(id);
 			}
 		};

org.eclipse.jgit/src/org/eclipse/jgit/blame/ReverseWalk.java

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/blame/ReverseWalk.java b/org.eclipse.jgit/src/org/eclipse/jgit/blame/ReverseWalk.java
index fafc4fb..582313f 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/blame/ReverseWalk.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/blame/ReverseWalk.java
@@ -36,7 +36,7 @@ public ReverseCommit next() throws MissingObjectException,
 	}
 
 	@Override
-	protected RevCommit createCommit(AnyObjectId id) {
+	protected RevCommit createCommit(AnyObjectId id, int graphPos) {
 		return new ReverseCommit(id);
 	}
 

org.eclipse.jgit/src/org/eclipse/jgit/revplot/PlotWalk.java

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/revplot/PlotWalk.java b/org.eclipse.jgit/src/org/eclipse/jgit/revplot/PlotWalk.java
index c8c454a..99022f0 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/revplot/PlotWalk.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/revplot/PlotWalk.java
@@ -105,7 +105,7 @@ public void sort(RevSort s, boolean use) {
 	}
 
 	@Override
-	protected RevCommit createCommit(AnyObjectId id) {
+	protected RevCommit createCommit(AnyObjectId id, int graphPos) {
 		return new PlotCommit(id);
 	}
 

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

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/DepthWalk.java b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/DepthWalk.java
index 7795ce2..442087d 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/DepthWalk.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/DepthWalk.java
@@ -196,7 +196,7 @@ public void markRoot(RevCommit c) throws MissingObjectException,
 		}
 
 		@Override
-		protected RevCommit createCommit(AnyObjectId id) {
+		protected RevCommit createCommit(AnyObjectId id, int graphPos) {
 			return new Commit(id);
 		}
 
@@ -367,7 +367,7 @@ public void markUnshallow(RevObject c) throws MissingObjectException,
 		}
 
 		@Override
-		protected RevCommit createCommit(AnyObjectId id) {
+		protected RevCommit createCommit(AnyObjectId id, int graphPos) {
 			return new Commit(id);
 		}
 

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

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RevWalk.java b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RevWalk.java
index 8e604ba..4f558bc 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RevWalk.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/revwalk/RevWalk.java
@@ -1764,12 +1764,27 @@ public ObjectWalk toObjectWalkWithSameObjects() {
 	 * @param id
 	 *            the object this walker requires a commit reference for.
 	 * @return a new unparsed reference for the object.
+	 *
+	 * @nooverride Since 7.8 This method is not intended to be re-implemented or
+	 *             extended by clients. Override
+	 *             {@link #createCommit(AnyObjectId, int)} instead.
 	 */
 	protected RevCommit createCommit(AnyObjectId id) {
 		return createCommit(id, commitGraph().findGraphPosition(id));
 	}
 
-	private RevCommit createCommit(AnyObjectId id, int graphPos) {
+	/**
+	 * Construct a new unparsed commit for the given object.
+	 *
+	 * @param id
+	 *            the object this walker requires a commit reference for.
+	 * @param graphPos
+	 *            the position of the commit in the commit graph or {@code -1}
+	 *            if the commit is not present in the commit graph
+	 * @return a new unparsed reference for the object.
+	 * @since 7.8
+	 */
+	protected RevCommit createCommit(AnyObjectId id, int graphPos) {
 		if (graphPos >= 0) {
 			return new RevCommitCG(id, graphPos);
 		}