QueryBusyException
A query its store's QueryBulkhead did not admit: the store already runs maxConcurrent queries, so this one was not run. QueryErrors.BUSY (HTTP 429, with Retry-After); the same query may pass later. The message names no store: its name is the server's configuration. Its cause is a StorageBusyException naming the store, which a subscription handler that ran the query retries as backpressure.