small fixes

Author: lbalmaceda

lib/src/main/java/com/auth0/authentication/AuthenticationAPIClient.java

@@ -485,14 +485,13 @@ private ParameterizableRequest<UserProfile> profileRequest() {
                 .build();
 
         return factory.POST(url, client, mapper, UserProfile.class);
-
     }
 
     private AuthenticationRequest newAuthenticationRequest(Map<String, Object> parameters) {
         final ParameterizableRequest<Token> credentialsRequest = loginWithResourceOwner();
-        credentialsRequest.getParameterBuilder().addAll(parameters);
         final ParameterizableRequest<UserProfile> profileRequest = profileRequest();
 
-        return new AuthenticationRequest(credentialsRequest, profileRequest);
+        return new AuthenticationRequest(credentialsRequest, profileRequest)
+                .addParameters(parameters);
     }
 }

lib/src/main/java/com/auth0/internal/BaseRequest.java

@@ -111,14 +111,6 @@ protected APIException parseUnsuccessfulResponse(Response response) {
         }
     }
 
-    private static abstract class CallbackTask<T> implements Runnable {
-        protected final BaseCallback<T> callback;
-
-        protected CallbackTask(BaseCallback<T> callback) {
-            this.callback = callback;
-        }
-    }
-
     @Override
     public void onFailure(Request request, IOException e) {
         postOnFailure(new Auth0Exception("Failed to execute request to " + url.toString(), e));