Make android_app.stem overridable

override_android_app can set "stem" property to set the APK name.

Bug: 193504286
Test: m (soong test)
Change-Id: I9ad66ea28bd1b030cb2c588d1f070d72e62ab1c7

java/base.go

@@ -253,9 +253,6 @@ type DeviceProperties struct {
 	// otherwise provides defaults libraries to add to the bootclasspath.
 	System_modules *string
 
-	// set the name of the output
-	Stem *string
-
 	IsSDKLibrary bool `blueprint:"mutated"`
 
 	// If true, generate the signature file of APK Signing Scheme V4, along side the signed APK file.
@@ -267,6 +264,15 @@ type DeviceProperties struct {
 	SyspropPublicStub string `blueprint:"mutated"`
 }
 
+// Device properties that can be overridden by overriding module (e.g. override_android_app)
+type OverridableDeviceProperties struct {
+	// set the name of the output. If not set, `name` is used.
+	// To override a module with this property set, overriding module might need to set this as well.
+	// Otherwise, both the overridden and the overriding modules will have the same output name, which
+	// can cause the duplicate output error.
+	Stem *string
+}
+
 // Functionality common to Module and Import
 //
 // It is embedded in Module so its functionality can be used by methods in Module
@@ -389,6 +395,8 @@ type Module struct {
 	protoProperties  android.ProtoProperties
 	deviceProperties DeviceProperties
 
+	overridableDeviceProperties OverridableDeviceProperties
+
 	// jar file containing header classes including static library dependencies, suitable for
 	// inserting into the bootclasspath/classpath of another compile
 	headerJarFile android.Path
@@ -544,6 +552,7 @@ func (j *Module) addHostAndDeviceProperties() {
 	j.addHostProperties()
 	j.AddProperties(
 		&j.deviceProperties,
+		&j.overridableDeviceProperties,
 		&j.dexer.dexProperties,
 		&j.dexpreoptProperties,
 		&j.linter.properties,
@@ -1671,7 +1680,7 @@ func (j *Module) ShouldSupportSdkVersion(ctx android.BaseModuleContext, sdkVersi
 }
 
 func (j *Module) Stem() string {
-	return proptools.StringDefault(j.deviceProperties.Stem, j.Name())
+	return proptools.StringDefault(j.overridableDeviceProperties.Stem, j.Name())
 }
 
 func (j *Module) JacocoReportClassesFile() android.Path {