Make aconfig flags generate a library instead of a srcjar.

Also add unit tests for the rest of device_config

Bug: 283475679
Test: m nothing (soong unit tests)
Change-Id: Iee18a1f2f2cbb23e8c8d84c54e903b32be29a693
diff --git a/java/generated_java_library.go b/java/generated_java_library.go
new file mode 100644
index 0000000..1b3de9f
--- /dev/null
+++ b/java/generated_java_library.go
@@ -0,0 +1,94 @@
+// Copyright 2023 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package java
+
+import (
+	"android/soong/android"
+)
+
+type GeneratedJavaLibraryModule struct {
+	Library
+	callbacks  GeneratedJavaLibraryCallbacks
+	moduleName string
+}
+
+type GeneratedJavaLibraryCallbacks interface {
+	// Called from inside DepsMutator, gives a chance to AddDependencies
+	DepsMutator(module *GeneratedJavaLibraryModule, ctx android.BottomUpMutatorContext)
+
+	// Called from inside GenerateAndroidBuildActions. Add the build rules to
+	// make the srcjar, and return the path to it.
+	GenerateSourceJarBuildActions(ctx android.ModuleContext) android.Path
+}
+
+// GeneratedJavaLibraryModuleFactory provides a utility for modules that are generated
+// source code, including ones outside the java package to build jar files
+// from that generated source.
+//
+// To use GeneratedJavaLibraryModule, call GeneratedJavaLibraryModuleFactory with
+// a callback interface and a properties object to add to the module.
+//
+// These modules will have some properties blocked, and it will be an error if
+// modules attempt to set them. See the list of property names in GeneratedAndroidBuildActions
+// for the list of those properties.
+func GeneratedJavaLibraryModuleFactory(moduleName string, callbacks GeneratedJavaLibraryCallbacks, properties interface{}) android.Module {
+	module := &GeneratedJavaLibraryModule{
+		callbacks:  callbacks,
+		moduleName: moduleName,
+	}
+	module.addHostAndDeviceProperties()
+	module.initModuleAndImport(module)
+	android.InitApexModule(module)
+	android.InitBazelModule(module)
+	InitJavaModule(module, android.HostAndDeviceSupported)
+	if properties != nil {
+		module.AddProperties(properties)
+	}
+	return module
+}
+
+func (module *GeneratedJavaLibraryModule) DepsMutator(ctx android.BottomUpMutatorContext) {
+	module.callbacks.DepsMutator(module, ctx)
+	module.Library.DepsMutator(ctx)
+}
+
+func checkPropertyEmpty(ctx android.ModuleContext, module *GeneratedJavaLibraryModule, name string, value []string) {
+	if len(value) != 0 {
+		ctx.PropertyErrorf(name, "%s not allowed on %s", name, module.moduleName)
+	}
+}
+
+func (module *GeneratedJavaLibraryModule) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	// These modules are all-generated, so disallow these properties to keep it simple.
+	// No additional sources
+	checkPropertyEmpty(ctx, module, "srcs", module.Library.properties.Srcs)
+	checkPropertyEmpty(ctx, module, "common_srcs", module.Library.properties.Common_srcs)
+	checkPropertyEmpty(ctx, module, "exclude_srcs", module.Library.properties.Exclude_srcs)
+	checkPropertyEmpty(ctx, module, "java_resource_dirs", module.Library.properties.Java_resource_dirs)
+	checkPropertyEmpty(ctx, module, "exclude_java_resource_dirs", module.Library.properties.Exclude_java_resource_dirs)
+	// No additional libraries. The generator should add anything necessary automatically
+	// by returning something from ____ (TODO: Additional libraries aren't needed now, so
+	// these are just blocked).
+	checkPropertyEmpty(ctx, module, "libs", module.Library.properties.Libs)
+	checkPropertyEmpty(ctx, module, "static_libs", module.Library.properties.Static_libs)
+	// Restrict these for no good reason other than to limit the surface area. If there's a
+	// good use case put them back.
+	checkPropertyEmpty(ctx, module, "plugins", module.Library.properties.Plugins)
+	checkPropertyEmpty(ctx, module, "exported_plugins", module.Library.properties.Exported_plugins)
+
+	srcJarPath := module.callbacks.GenerateSourceJarBuildActions(ctx)
+	module.Library.properties.Generated_srcjars = append(module.Library.properties.Generated_srcjars, srcJarPath)
+	module.Library.GenerateAndroidBuildActions(ctx)
+}