Values.BrokerInstanceOptionSourceOption for host instance type.
type nonrec t = {availabilityZones : AvailabilityZone.t list option;The list of available az.
*)engineType : EngineType.t option;The broker's engine type.
*)hostInstanceType : string option;The broker's instance type.
*)storageType : BrokerStorageType.t option;The broker's storage type.
*)supportedDeploymentModes : DeploymentMode.t list option;The list of supported deployment modes.
*)supportedEngineVersions : string list option;The list of supported engine versions.
*)}