Access local file in a WebView

I’m trying to load a local leaflet map in a webview. The local html and resources (js, css) load fine, but then some information for the map has to be loaded from a json (geojson) local file.
The json local file is not loaded into the map, I guess it’s a CORS issue.

I tried to set these properties to the webview:

webView:setNativeProperty( “allowFileAccessFromFileURLs”, true )
webView:setNativeProperty( “allowUniversalAccessFromFileURLs”, true )

I’m not sure if these are the right settings or if there’s something else that I can try to load the local json file so it could be used by javascript to add information to the map.