Channel associated with this client.

Can be used to register a custom header interceptor. The interceptor is invoked each time a new call on this client is started. It is not recommented to use header interceptor to add auth headers to RPC calls.

gRPC supports multiple "hosts" being served by a single server. This property can be used to set the target host explicitly. By default, this will be set to null with the meaning "use default host".