DataSource Filtering

Is there a way to specify a filter property like the one I tried to set in this data source?

ui module MyPackageUi {
    dataSource DashboardSibiloSource {
        "collection": true,
        "record": false,
        "c3type": "MyPackageTdUseCase",
        "c3function": "fetch",
        "responseSelector": "objs.sibilo",
        "c3arguments": {
            "spec": {
                "filter":"Filter.eq('asset.id', 'XXX').and.exists('latestModel')", 
                "include":"sibilo",
                "limit": -1
            }
        }
    }
}

The filter works on Console but not in the UI:

MyPackageTdUseCase.fetch({
                "filter":Filter.eq('asset.id', 'assetName').and.exists('latestModel'), 
                "include":"sibilo",
                "limit": -1
            })

Filter is an expression builder for the query filter expressions. It’s a static JavaScript object. You could use the toString function and use the expression result directly in your .c3ui file.