Resolver implements AutoCloseable

jDnsProxy/src/main/java/com/moparisthebest/dns/resolve/CacheResolver.java

@@ -50,11 +50,6 @@ public class CacheResolver implements Resolver, AutoCloseable {
         return this;
     }
 
-    @Override
-    public void close() {
-
-    }
-
     private class CachedPacket {
         final Packet response;
         final long receivedSeconds, expiredSeconds;

jDnsProxy/src/main/java/com/moparisthebest/dns/resolve/DelegatingQueueProcessingResolver.java

@@ -23,4 +23,10 @@ public class DelegatingQueueProcessingResolver extends AbstractQueueProcessingRe
     public Packet resolve(final Packet request) throws Exception {
         return delegate.resolve(request);
     }
+
+    @Override
+    public void close() {
+        super.close();
+        delegate.close();
+    }
 }

jDnsProxy/src/main/java/com/moparisthebest/dns/resolve/Resolver.java

@@ -13,7 +13,7 @@ import java.util.concurrent.Executor;
  *
  * Ideally, implementations provide optimized versions of both the in-line and async call.
  */
-public interface Resolver {
+public interface Resolver extends AutoCloseable {
 
     /**
      * This must return immediately and resolve the DNS query in the background, using the given executor
@@ -45,6 +45,10 @@ public interface Resolver {
         return resolveAsync(new BaseRequestResponse(request), Runnable::run).get().getResponse();
     }
 
+    default void close() {
+        // do nothing by default
+    }
+
     ServiceLoader<Services> services = ServiceLoader.load(Services.class);
 
     static Resolver of(final ParsedUrl parsedUrl) {