src/java.base/share/classes/java/util/concurrent/SynchronousQueue.java

*** 1098,1107 ****
--- 1098,1108 ----
      }
  
      /**
       * Always returns {@code "[]"}.
       * @return {@code "[]"}
+      * @since 9
       */
      public String toString() {
          return "[]";
      }