Implement a getter for the AsyncHttpClientConfig on AsyncHttpClient, close AsyncHttpClient#1420 (AsyncHttpClient#1422)

Author: atehrani

client/src/main/java/org/asynchttpclient/AsyncHttpClient.java

@@ -281,4 +281,10 @@ public interface AsyncHttpClient extends Closeable {
      * @param predicate the predicate
      */
     void flushChannelPoolPartitions(Predicate<Object> predicate);
+
+    /**
+     * Return the config associated to this client.
+     * @return the config associated to this client.
+     */
+    AsyncHttpClientConfig getConfig();
 }

client/src/main/java/org/asynchttpclient/DefaultAsyncHttpClient.java

@@ -276,4 +276,9 @@ protected BoundRequestBuilder requestBuilder(String method, String url) {
     protected BoundRequestBuilder requestBuilder(Request prototype) {
         return new BoundRequestBuilder(this, prototype).setSignatureCalculator(signatureCalculator);
     }
+
+    @Override
+    public AsyncHttpClientConfig getConfig() {
+        return this.config;
+    }
 }

extras/registry/src/test/java/org/asynchttpclient/extras/registry/BadAsyncHttpClient.java

@@ -138,4 +138,9 @@ public ClientStats getClientStats() {
     public void flushChannelPoolPartitions(Predicate<Object> predicate) {
         throw new UnsupportedOperationException();
     }
+
+    @Override
+    public AsyncHttpClientConfig getConfig() {
+        return null;
+    }
 }

extras/registry/src/test/java/org/asynchttpclient/extras/registry/TestAsyncHttpClient.java

@@ -134,4 +134,9 @@ public ClientStats getClientStats() {
     public void flushChannelPoolPartitions(Predicate<Object> predicate) {
         throw new UnsupportedOperationException();
     }
+
+    @Override
+    public AsyncHttpClientConfig getConfig() {
+        return null;
+    }
 }