fallbackUrl property
Fallback URL template, used if an error occurs when fetching tiles from the urlTemplate.
Note that specifying this (non-null) will result in tiles not being cached in memory. This is to avoid issues where the urlTemplate is flaky, to prevent different tilesets being displayed at the same time.
It is expected that this follows the same retina support behaviour as urlTemplate.
Avoid specifying this when using AssetTileProvider or FileTileProvider, as these providers are less performant and efficient when this is specified. See their documentation for more information.
Implementation
final String? fallbackUrl;