ninja-core/src/main/java/ninja/AssetsController.java
public Result serveStatic() {
        Object renderable = new Renderable() {
            @Override
            public void render(Context context, Result result) {
                String fileName = getFileNameFromPathOrReturnRequestPath(context);
                URL url = getStaticFileFromAssetsDir(fileName);
                streamOutUrlEntity(url, context, result);
            }
        };
        return Results.ok().render(renderable);
    }
public Result serveStatic() {
        Object renderable = new Renderable() {
            @Override
            public void render(Context context, Result result) {
                String fileName = getFileNameFromPathOrReturnRequestPath(context);
                URL url = getStaticFileFromAssetsDir(fileName);
                streamOutUrlEntity(url, context, result);
            }
        };
        return Results.ok().render(renderable);
    }
Serves resources from the assets directory of your application.

For instance:
route: /robots.txt
A request to /robots.txt will be served from /assets/robots.txt.

You can also use a path like the following to serve files:
route: /assets/{fileName: .*}

matches
/assets/app/app.css
and will return
/assets/app/app.css (from your jar).