Fixes invalid JavaDoc for DeferredWorker (#14625)

Change-Id: I479f9e743849abf63ca898a7d6b11e4d4f94dada

client/src/com/vaadin/client/DeferredWorker.java

@@ -26,8 +26,11 @@ package com.vaadin.client;
  */
 public interface DeferredWorker {
     /**
-     * @returns true, if there are operations pending which must be executed
-     *          before reaching a steady state
+     * Checks whether there are operations pending for this widget that must be
+     * executed before reaching a steady state.
+     * 
+     * @returns <code>true</code> iff there are operations pending which must be
+     *          executed before reaching a steady state
      */
     public boolean isWorkPending();
 }