Install generated plugin code into the API module.

pluginator/go.mod

@@ -2,4 +2,13 @@ module sigs.k8s.io/kustomize/pluginator
 
 go 1.13
 
-require sigs.k8s.io/kustomize/v3 v3.3.1
+require (
+	github.com/emicklei/go-restful v2.9.6+incompatible // indirect
+	github.com/google/gofuzz v1.0.0 // indirect
+	github.com/googleapis/gnostic v0.3.0 // indirect
+	github.com/json-iterator/go v1.1.6 // indirect
+	github.com/mailru/easyjson v0.0.0-20190620125010-da37f6c1e481 // indirect
+	github.com/modern-go/reflect2 v1.0.1 // indirect
+	k8s.io/klog v0.3.3 // indirect
+	sigs.k8s.io/kustomize/v3 v3.3.1
+)

pluginator/main.go

@@ -48,7 +48,8 @@ func main() {
 		fmt.Sprintf(
 			"// pluginator %+v\n", provenance.GetProvenance()))
 	w.write("\n")
-	w.write("package " + plugins.BuiltinPluginPackage)
+	// TODO: `builtins` should be a const?
+	w.write("package builtins")
 
 	pType := unknown
 
@@ -124,8 +125,7 @@ func makeOutputFileName(root string) string {
 		"src",
 		pgmconfig.DomainName,
 		pgmconfig.ProgramName,
-		pgmconfig.PluginRoot,
-		plugins.BuiltinPluginPackage,
+		"api", "plugins", "builtins",
 		root+".go")
 }