Add method to IFoo for testing NULL interfaces.

Bug: 32410513
Test: mma, hidl_test
Change-Id: I791c3a95e670a859e5e494ead987d2a93f5047a5
diff --git a/tests/bar/1.0/default/Bar.cpp b/tests/bar/1.0/default/Bar.cpp
index b960524..0257ee0 100644
--- a/tests/bar/1.0/default/Bar.cpp
+++ b/tests/bar/1.0/default/Bar.cpp
@@ -142,6 +142,10 @@
     return mFoo->closeHandles();
 }
 
+Return<void> Bar::echoNullInterface(const sp<IFooCallback> &cb, echoNullInterface_cb _hidl_cb) {
+    return mFoo->echoNullInterface(cb, _hidl_cb);
+}
+
 // Methods from ::android::hardware::tests::bar::V1_0::IBar follow.
 Return<void> Bar::thisIsNew()  {
     ALOGI("SERVER(Bar) thisIsNew");