DfsPackFile: make #getReverseIdx public

The DfsPackFile#getReverseIdx method, which wraps creating a
PackReverseIndex in caching, was package-private. This caused
implementations on top of DfsPackFile to directly instantiate a
PackReverseIndex in cases where it would benefit from caching.

Instead, make #getReverseIdx public so that the caching logic can be
reused by implementations where appropriate.

Change-Id: I4553e514a4ac320bfe2455c00023343ad97f9d15
Signed-off-by: Anna Papitto <annapapitto@google.com>
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java
index 7e1f0ad..f61f8c6 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java
@@ -259,7 +259,17 @@ public CommitGraph getCommitGraph(DfsReader ctx) throws IOException {
 		return commitGraph;
 	}
 
-	PackReverseIndex getReverseIdx(DfsReader ctx) throws IOException {
+	/**
+	 * Get the PackReverseIndex for this PackFile.
+	 *
+	 * @param ctx
+	 *            reader context to support reading from the backing store if
+	 *            the index is not already loaded in memory
+	 * @return the PackReverseIndex
+	 * @throws java.io.IOException
+	 *             the pack index is not available, or is corrupt
+	 */
+	public PackReverseIndex getReverseIdx(DfsReader ctx) throws IOException {
 		if (reverseIndex != null) {
 			return reverseIndex;
 		}