Ensure java_system_modules_import uses prebuilts

Make sure that java_system_modules_import always depends on the
prebuilt by adding dependencies in the ComponentDepsMutator() method
which is called before prebuilts without a corresponding source are
renamed from prebuilt_<x> to <x>. That requires the prebuilt_ prefix
to be provided but it ensures that the dependencies are safe.

Similar logic also makes sure java_system_modules always depends on
the source module and not on a renamed prebuilt module.

Bug: 182402568
Test: m nothing
Change-Id: I30db95978f5d9b205951011edf40585ee36c0c4c
diff --git a/java/system_modules.go b/java/system_modules.go
index 95f71b8..8c69051 100644
--- a/java/system_modules.go
+++ b/java/system_modules.go
@@ -169,7 +169,13 @@
 	system.outputDir, system.outputDeps = TransformJarsToSystemModules(ctx, jars)
 }
 
-func (system *SystemModules) DepsMutator(ctx android.BottomUpMutatorContext) {
+// ComponentDepsMutator is called before prebuilt modules without a corresponding source module are
+// renamed so unless the supplied libs specifically includes the prebuilt_ prefix this is guaranteed
+// to only add dependencies on source modules.
+//
+// The systemModuleLibsTag will prevent the prebuilt mutators from replacing this dependency so it
+// will never be changed to depend on a prebuilt either.
+func (system *SystemModules) ComponentDepsMutator(ctx android.BottomUpMutatorContext) {
 	ctx.AddVariationDependencies(nil, systemModulesLibsTag, system.properties.Libs...)
 }
 
@@ -225,6 +231,15 @@
 	return &system.prebuilt
 }
 
+// ComponentDepsMutator is called before prebuilt modules without a corresponding source module are
+// renamed so as this adds a prebuilt_ prefix this is guaranteed to only add dependencies on source
+// modules.
+func (system *systemModulesImport) ComponentDepsMutator(ctx android.BottomUpMutatorContext) {
+	for _, lib := range system.properties.Libs {
+		ctx.AddVariationDependencies(nil, systemModulesLibsTag, "prebuilt_"+lib)
+	}
+}
+
 type systemModulesSdkMemberType struct {
 	android.SdkMemberTypeBase
 }