The routing key (in binary raw form) to use for token aware routing of this query.

The routing key is optional in the sense that implementers are free to return null. The routing key is an hint used for token aware routing (see TokenAwarePolicy), and if provided should correspond to the binary value for the query partition key. However, not providing a routing key never causes a query to fail and if the load balancing policy used is not token aware, then the routing key can be safely ignored.

public abstract RoutingKey RoutingKey { get; }