improve javadoc

Author: vladak

opengrok-indexer/src/main/java/org/opengrok/indexer/util/LazilyInstantiate.java

@@ -95,7 +95,9 @@ private LazilyInstantiate(Supplier<T> supplier) {
         this.current = this::swapper;
     }
 
-    //swaps the itself out for a supplier of an instantiated object
+    /**
+     * Swaps itself out for a supplier of an instantiated object.
+     */
     private synchronized T swapper() {
         if (!(current instanceof Factory)) {
             T obj = supplier.get();