use the @deprecated javadoc tag

Author: Vladimir Kotal

opengrok-indexer/src/main/java/org/opengrok/indexer/history/HistoryEntry.java

@@ -179,8 +179,9 @@ public void setFiles(SortedSet<String> files) {
     }
 
     /**
-     * The method is kept only for backward compatibility to avoid warnings when deserializing objects
-     * from the previous format. The tags were moved to the {@link History} class.
+     * @deprecated The method is kept only for backward compatibility to avoid warnings when deserializing objects
+     * from the previous format.
+     * The tags were moved to the {@link History} class.
      * Will be removed sometime after the OpenGrok 1.8.0 version.
      */
     @Deprecated(since = "1.7.11", forRemoval = true)