title: Force close when try to Invoke method
body: <p>I have a problem when I try to set up the client, I got the message: toString() failure in the factory.build.
  Method threw 'java.lang.IllegalArgumentException' exception. Cannot evaluate $Proxy1.toString() then when i call</p>
  
  <pre><code>ApiClientFactory factory = new ApiClientFactory();
  factory.apiKey("xXxxXXXxxXXXXXXxxxxX");
  final APIGatewayPediuClient client = factory.build(APIGatewayPediuClient.class); // exception happened in this line, proxy throw exepction
  </code></pre>
  
  <p>and when i try invoke the method </p>
  
  <p><code>Places place = client.placesGet();</code></p>
  
  <p>force close happens </p>
  
  <pre><code>com.amazonaws.http.UrlHttpClient.createHttpResponse(UrlHttpClient.java:72)
  at com.amazonaws.http.UrlHttpClient.execute(UrlHttpClient.java:66)
  at com.amazonaws.mobileconnectors.apigateway.ApiClientHandler.invoke(ApiClientHandler.java:91)
  at java.lang.reflect.Proxy.invoke(Proxy.java:393)
  at $Proxy1.placesGet(Unknown Source)
  at net.devsoft.pediu.activity.HomeActivity$override.onCreate(HomeActivity.java:195)
  at net.devsoft.pediu.activity.HomeActivity$override.access$dispatch(HomeActivity.java)`
  </code></pre>
  
  <p>SDK version:</p>
  
  <pre><code>compile com.amazonaws:aws-android-sdk-core:2.2.6'
  compile 'com.amazonaws:aws-android-sdk-cognito:2.2.6'
  compile 'com.amazonaws:aws-android-sdk-apigateway-core:2.2.6'
  compile 'com.google.code.gson:son:1.7.2
  </code></pre>
  
  <p>but already tried with aws version 2.2.15 and still doesnt work, the SDK generate to Obj-C its working perfectly</p>