receive
abstract fun receiveVersionsDiff(packageName: String, versionsDiffMap: Map<String, <Error class: unknown class>?>?)
Receives the diff for all versions of the give n packageName as a map of versions IDs to the diff JsonObject. This is called once for each package in the index diff (if versions have changed).
If an entry in the given versionsDiffMap is null, the version with that ID should be removed.