Add a CMake target for the Messaging aar (#1205)

Author: a-maurice

messaging/CMakeLists.txt

@@ -109,6 +109,19 @@ endif()
 
 if(ANDROID)
   firebase_cpp_proguard_file(messaging)
+
+  # Expose the Messaging Java AAR file as a target
+  set(FIREBASE_MESSAGING_JAVA_AAR_PATH
+    "${CMAKE_CURRENT_LIST_DIR}/messaging_java/build/outputs/aar/messaging_java.aar")
+  firebase_cpp_gradle(":messaging:messaging_java:assemble"
+    "${FIREBASE_MESSAGING_JAVA_AAR_PATH}"
+  )
+  add_custom_target(firebase_messaging_java_aar
+    DEPENDS "${FIREBASE_MESSAGING_JAVA_AAR_PATH}"
+  )
+  set_target_properties(firebase_messaging_java_aar PROPERTIES
+    OBJECT_OUTPUTS "${FIREBASE_MESSAGING_JAVA_AAR_PATH}"
+  )
 elseif(IOS)
   # Enable Automatic Reference Counting (ARC) and Bitcode.
   target_compile_options(firebase_messaging