Rename method parameter to fix warning about hidden field

Change-Id: Id094ab022f82db0f3eb220052adc0aed1cde2d50
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/BitmapIndexImpl.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/BitmapIndexImpl.java
index 01bd826..ba69293 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/BitmapIndexImpl.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/BitmapIndexImpl.java
@@ -73,12 +73,12 @@
 	}
 
 	@Override
-	public void addBitmapLookupListener(BitmapLookupListener listener) {
-		if (listener == null) {
+	public void addBitmapLookupListener(BitmapLookupListener l) {
+		if (l == null) {
 			throw new IllegalArgumentException(
 					JGitText.get().bitmapUseNoopNoListener);
 		}
-		this.listener = listener;
+		this.listener = l;
 	}
 
 	int findPosition(AnyObjectId objectId) {