http: fix mvn findbugs:check error

https://codereview.appspot.com/10054046/

Author: Yaniv Inbar

google-http-client-test/src/main/java/com/google/api/client/test/json/AbstractJsonFactoryTest.java

@@ -23,6 +23,7 @@
 import com.google.api.client.json.JsonString;
 import com.google.api.client.json.JsonToken;
 import com.google.api.client.util.ArrayMap;
+import com.google.api.client.util.Beta;
 import com.google.api.client.util.Data;
 import com.google.api.client.util.Key;
 import com.google.api.client.util.NullValue;
@@ -60,6 +61,7 @@
  *
  * @author Yaniv Inbar
  */
+@Beta
 public abstract class AbstractJsonFactoryTest extends TestCase {
 
   public AbstractJsonFactoryTest(String name) {