src/java.base/share/classes/java/net/ResponseCache.java

@@ -59,10 +59,15 @@
  * @since 1.5
  */
 public abstract class ResponseCache {
 
     /**
+     * Constructor for subclasses to call.
+     */
+    public ResponseCache() {}
+
+    /**
      * The system wide cache that provides access to a url
      * caching mechanism.
      *
      * @see #setDefault(ResponseCache)
      * @see #getDefault()