Enforce specifying sdk/private for apps.

All apps in master comply with this now, but new offenders
are being added daily. This will ensure compliance going
forward.

Test: vendor/google/build/build_test.bash --dist
Bug: 73535841

Change-Id: Id3fbb502d26d91b64480fec74e241ba77fa0faff
diff --git a/core/sdk_check.mk b/core/sdk_check.mk
index 49ea2a8..c09fc7c 100644
--- a/core/sdk_check.mk
+++ b/core/sdk_check.mk
@@ -8,6 +8,11 @@
 
 whitelisted_modules := framework-res__auto_generated_rro
 
+
+ifeq (,$(JAVA_SDK_ENFORCEMENT_ERROR))
+  JAVA_SDK_ENFORCEMENT_ERROR := APPS
+endif
+
 ifeq ($(LOCAL_SDK_VERSION)$(LOCAL_PRIVATE_PLATFORM_APIS),)
   ifeq (,$(filter $(LOCAL_MODULE),$(whitelisted_modules)))
     ifneq ($(JAVA_SDK_ENFORCEMENT_WARNING)$(JAVA_SDK_ENFORCEMENT_ERROR),)