Update layer definition in webmap using ArcGIS API for Python 2.4+

[ClintonBradley]

Can someone explain how to access and update the contents of webmaps in version 2.4+ of the ArcGIS API for Python? I used to be able to use get_data() to access the operational layers and sublayers using the layers property and then use update() to update the original json file, but I can't seem to find how to do this with the new arcgis.map and arcgis.layers modules. Specifically I'm looking to configure popups and reorder/hide field names in the layer attribute tables. My maps feature Map Image Layers that contain multiple sublayers. Any help is much appreciated.

@PeterKnoop @Clubdebambos 

[ClintonBradley]

Update: I've found that if I add the sublayers to my webmap individually and then group them instead of just adding the grouped map service, I have access to a layers property in the group layer which seems to provide access to popup info. Hoping this isn't the requirement going forward.