fetch
open suspend override fun fetchAndCacheTile(z: Int, x: Int, y: Int, overrideCache: Boolean = false): Boolean
Bulk-download path: bypass isCacheOnly and force a network fetch + persist on cache miss. When overrideCache is true, also skip the cache hit short-circuit so every tile is re-downloaded. See earth.worldwind.layer.cache.CachedElevationSourceFactory.fetchAndCacheTile for the motivating contract.