Merge pull request #2345 from square/jw/2017-05-25/nullable

Add some missing nullable annotations.

retrofit-mock/src/main/java/retrofit2/mock/BehaviorDelegate.java

@@ -21,6 +21,7 @@ import java.lang.reflect.Method;
 import java.lang.reflect.Proxy;
 import java.lang.reflect.Type;
 import java.util.concurrent.ExecutorService;
+import javax.annotation.Nullable;
 import retrofit2.Call;
 import retrofit2.CallAdapter;
 import retrofit2.Retrofit;
@@ -46,7 +47,7 @@ public final class BehaviorDelegate<T> {
     this.service = service;
   }
 
-  public T returningResponse(Object response) {
+  public T returningResponse(@Nullable Object response) {
     return returning(Calls.response(response));
   }
 

retrofit-mock/src/main/java/retrofit2/mock/Calls.java

@@ -34,7 +34,7 @@ public final class Calls {
     return new DeferredCall<>(callable);
   }
 
-  public static <T> Call<T> response(T successValue) {
+  public static <T> Call<T> response(@Nullable T successValue) {
     return new FakeCall<>(Response.success(successValue), null);
   }