…1598)

* chore(demo): add DemoApplication for API key/Map ID validation

Introduces a centralized mechanism to validate the Maps API key and configure a Map ID, which is required for features like Advanced Markers.

This change adds a new `DemoApplication` class that runs two checks on startup:
- `checkApiKey()`: Validates that a non-default API key is present in the manifest metadata.
- `getMapId()`: Retrieves a Map ID, prioritizing `secrets.properties` (via `BuildConfig`) and falling back to `strings.xml`.

`BaseDemoActivity` is refactored to:
- Get the Map ID from `DemoApplication`.
- Programmatically create the `SupportMapFragment` using `GoogleMapOptions` to apply the `mapId`.

This replaces the previous method of inflating the map from an XML layout, which didn't allow for easy programmatic Map ID configuration.

Documentation in `README.md` is updated to reflect the new configuration options for setting the Map ID.

* chore: add missing header

* chore(demo): Initialize map fragment when map ID is null

Allows the demo application to run even when a map ID is not provided by instantiating the `SupportMapFragment` without `GoogleMapOptions`.

* chore: Reorder string resource to put map_id as last item

* chore: Adds a link to the map id documentation.

* docs: address review comment

* feat: added startCap and endCap to polyline

* feat: non-nullable

# [3.19.0](v3.18.0...v3.19.0) (2025-09-16)

### Features

* added cap to polyline ([#1603](#1603)) ([a33fab0](a33fab0))