open
Open (or create) a URI-keyed BlobStore — a flat key/value store for arbitrary HTTP payloads. Distinct from openImageTileStore / openFeatureStore in that entries are keyed by string URI rather than by (z, x, y) or a feature id, which makes it the right shape for caches whose entries are independent URLs.
First user: 3D Tiles content payloads (earth.worldwind.layer.ogc3d.Ogc3dTilesLayer) — each tileset.json and each tile content URI keys into one row. Future users: arbitrary HTTP asset caches.
Default returns NoOpBlobStore. Platform backends that have implemented a real persistence layer (GeoPackage on JVM/Android, IndexedDB on JS, file blobs on iOS) override this. Layers that cache to a NoOpBlobStore silently fall back to network-only fetches — caller code never has to branch on store availability.
See openImageTileStore for displayName semantics.