--- old/src/jdk.net/share/classes/jdk/net/ExtendedSocketOptions.java	2018-10-01 14:53:00.660549959 +0100
+++ new/src/jdk.net/share/classes/jdk/net/ExtendedSocketOptions.java	2018-10-01 14:53:00.332557524 +0100
@@ -206,7 +206,7 @@
 
                 if (option == SO_FLOW_SLA) {
                     assert flowSupported;
-                    SocketFlow flow = checkValueType(value, option.type());
+                    SocketFlow flow = checkValueType(value, SocketFlow.class);
                     setFlowOption(fd, flow);
                 } else if (option == TCP_QUICKACK) {
                     setQuickAckOption(fd, (boolean) value);
@@ -254,12 +254,12 @@
     }
 
     @SuppressWarnings("unchecked")
-    private static <T> T checkValueType(Object value, Class<?> type) {
+    private static <T, U extends T> U checkValueType(Object value, Class<T> type) {
         if (!type.isAssignableFrom(value.getClass())) {
             String s = "Found: " + value.getClass() + ", Expected: " + type;
             throw new IllegalArgumentException(s);
         }
-        return (T) value;
+        return (U) value;
     }
 
     private static final JavaIOFileDescriptorAccess fdAccess =