remove redundant instanceof

Author: diegomarquezp

google-http-client-apache-v3/src/main/java/com/google/api/client/http/apache/v3/ApacheHttpTransport.java

@@ -216,9 +216,7 @@ protected ApacheHttpRequest buildRequest(String method, String url) {
    */
   @Override
   public void shutdown() throws IOException {
-    if (httpClient instanceof CloseableHttpClient) {
-      ((CloseableHttpClient) httpClient).close();
-    }
+    httpClient.close();
   }
 
   /**