More precise generics for CloseShieldChannelHandler.SUPPORTED_INTERFACES

Author: garydgregory

src/main/java/org/apache/commons/io/channels/CloseShieldChannelHandler.java

@@ -39,10 +39,10 @@
 
 final class CloseShieldChannelHandler implements InvocationHandler {
 
-    private static final Set<Class<?>> SUPPORTED_INTERFACES;
+    private static final Set<Class<? extends Channel>> SUPPORTED_INTERFACES;
 
     static {
-        final Set<Class<?>> interfaces = new HashSet<>();
+        final Set<Class<? extends Channel>> interfaces = new HashSet<>();
         interfaces.add(AsynchronousChannel.class);
         interfaces.add(ByteChannel.class);
         interfaces.add(Channel.class);