diff --git a/lucene/core/src/java/org/apache/lucene/index/IndexDeletionPolicy.java b/lucene/core/src/java/org/apache/lucene/index/IndexDeletionPolicy.java
index ca04f30bd37..a5b0aabf3ec 100644
--- a/lucene/core/src/java/org/apache/lucene/index/IndexDeletionPolicy.java
+++ b/lucene/core/src/java/org/apache/lucene/index/IndexDeletionPolicy.java
@@ -78,6 +78,8 @@ public abstract class IndexDeletionPolicy implements Cloneable {
    * @param commits List of current 
    * {@link IndexCommit point-in-time commits},
    *  sorted by age (the 0th one is the oldest commit).
+   *  Note that for a new index this method is invoked with
+   *  an empty list.
    */
   public abstract void onInit(List<? extends IndexCommit> commits) throws IOException;