Fix link-type check warning on com.android.nfc_extras

The library has been built without SDK, and is used by an app
NfcExtrasTests that is built with SDK. Such this SDK -> non-SDK
dependency has been causing link-type check warnings, which will turn
into errors soon.

This change fixes the warning by making a stub library
com.android.nfc_extras.stubs from the runtime library and let the app to
link against the stub library. Since the stubs library does not use any
private APIs, it is built with SDK.

Bug: 69899800
Test: m -j NfcExtrasTests is successful and does not show any link-type
check warning.

Change-Id: I57980ccbc9036d7cc6df114a975a384d10a2962b

nfc-extras/Android.mk

@@ -1,13 +1,33 @@
 LOCAL_PATH:= $(call my-dir)
 
 include $(CLEAR_VARS)
-
+LOCAL_MODULE := com.android.nfc_extras
 LOCAL_MODULE_TAGS := optional
+LOCAL_SRC_FILES := $(call all-java-files-under,java)
+include $(BUILD_JAVA_LIBRARY)
 
-LOCAL_SRC_FILES := $(call all-java-files-under, java)
-
-LOCAL_MODULE:= com.android.nfc_extras
+include $(CLEAR_VARS)
+LOCAL_MODULE := com.android.nfc_extras-stubs-gen
+LOCAL_MODULE_CLASS := JAVA_LIBRARIES
+LOCAL_SRC_FILES := $(call all-java-files-under,java)
+# This is to reference SdkConstant annotation; not part of this lib.
+LOCAL_DROIDDOC_SOURCE_PATH := frameworks/base/core/java/android/annotation
+LOCAL_DROIDDOC_STUB_OUT_DIR := $(TARGET_OUT_COMMON_INTERMEDIATES)/JAVA_LIBRARIES/com.android.nfc_extras.stubs_intermediates/src
+LOCAL_DROIDDOC_OPTIONS:= \
+    -hide 111 -hide 113 -hide 125 -hide 126 -hide 127 -hide 128 \
+    -stubpackages com.android.nfc_extras \
+    -nodocs
+LOCAL_UNINSTALLABLE_MODULE := true
+include $(BUILD_DROIDDOC)
+com_android_nfc_extras_gen_stamp := $(full_target)
 
-include $(BUILD_JAVA_LIBRARY)
+include $(CLEAR_VARS)
+LOCAL_MODULE := com.android.nfc_extras.stubs
+# This is to reference SdkConstant annotation; not part of this lib.
+LOCAL_SRC_FILES := ../core/java/android/annotation/SdkConstant.java
+LOCAL_SDK_VERSION := current
+LOCAL_ADDITIONAL_DEPENDENCIES := $(com_android_nfc_extras_gen_stamp)
+com_android_nfc_extras_gen_stamp :=
+include $(BUILD_STATIC_JAVA_LIBRARY)
 
 include $(call all-makefiles-under,$(LOCAL_PATH))

nfc-extras/tests/Android.mk

@@ -20,7 +20,7 @@ LOCAL_MODULE_TAGS := tests
 
 LOCAL_JAVA_LIBRARIES := \
     android.test.runner.stubs \
-    com.android.nfc_extras \
+    com.android.nfc_extras.stubs \
     android.test.base.stubs
 
 LOCAL_STATIC_JAVA_LIBRARIES := junit