PlayFramework: adding assets on compiling - scala

Question

in our Scala project we're using Play Framework with some static assets in the public directory, linked in the normal way:
via "routes":
GET /assets/*file controllers.Assets.versioned(path="/public", file: Asset)
and in the "index.scala.hml":
<script type="text/javascript" src="#routes.Assets.versioned("javascripts/main.js")">
Now we want to use a submodule written in nodejs, which should create other js files on compiling, and put them to the assets folder.
We were able to run npm commands in the "build.sbt" file:
buildSubmodules := {
val s: TaskStreams = streams.value
val shell: Seq[String] = if (sys.props("os.name").contains("Windows")) Seq("cmd", "/c") else Seq("bash", "-c")
val npmInstall: Seq[String] = shell :+ "npm --prefix submodules/ install"
val npmBuild: Seq[String] = shell :+ "npm --prefix submodules/ run build"
s.log.info("building submodules...")
if((npmInstall #&& npmBuild !) == 0) {
s.log.success("submodules build successful!")
} else {
throw new IllegalStateException("submodules build failed!")
}
}
(Compile / compile) := ((Compile / compile) dependsOn buildSubmodules).value
and also included in the "index.scala.html":
<link rel="stylesheet" href="#routes.Assets.versioned("submodules/main.css")" />
but new created files still cannot be found in the "public/assets" folder after compilation finished.
Is there any way to add these assets to compiled project?
Thank you