Replace JacksonFactory with GsonFactory.

endpoints-framework/build.gradle

@@ -87,9 +87,8 @@ dependencies {
   compile group: 'com.google.appengine', name: 'appengine-api-1.0-sdk', version: appengineVersion
   compile group: 'com.google.flogger', name: 'flogger', version: floggerVersion
   runtime group: 'com.google.flogger', name: 'flogger-system-backend', version: floggerVersion
-  compile(group: 'com.google.http-client', name: 'google-http-client-jackson2', version: apiclientVersion) {
+  compile(group: 'com.google.http-client', name: 'google-http-client-gson', version: apiclientVersion) {
     exclude group: 'com.google.guava', module: 'guava-jdk5'
-    exclude group: 'com.fasterxml.jackson.core', module: 'jackson-core'
   }
   compile(group: 'com.google.api-client', name: 'google-api-client', version: apiclientVersion) {
     exclude group: 'com.google.guava', module: 'guava-jdk5'

endpoints-framework/src/main/java/com/google/api/server/spi/Client.java

@@ -23,7 +23,7 @@
 import com.google.api.client.http.javanet.NetHttpTransport;
 import com.google.api.client.json.JsonFactory;
 import com.google.api.client.json.JsonObjectParser;
-import com.google.api.client.json.jackson2.JacksonFactory;
+import com.google.api.client.json.gson.GsonFactory;
 import com.google.common.annotations.VisibleForTesting;
 
 /**
@@ -43,7 +43,7 @@ public class Client {
     } else {
       transport = new NetHttpTransport();
     }
-    jsonFactory = new JacksonFactory();
+    jsonFactory = GsonFactory.getDefaultInstance();
     jsonHttpRequestFactory = transport.createRequestFactory(new HttpRequestInitializer() {
       @Override
       public void initialize(HttpRequest request) {