The extent that constrains the display to a specific region. The max extent is initialized when the map loads or when you set it explicitly. This value limits panning in the MapView to a specific area of the map.
If the max extent is null when the map loads, or you set it to null, max extent is calculated from the union of the full extent of all basemap layers. If there is no basemap, it is set as the full extent of the map's first operational layer.
If the GeoModel.initialViewpoint is not set, the max extent is used as the initial viewpoint. If the GeoModel.initialViewpoint is set, but is outside of the max extent, the max extent takes precedence and the display will initially show the max extent.