JIRA: https://jira.spring.io/browse/INT-4057
When general router `channelKey` returns just a `Class<?>` result, we end up with the
`unsupported return type for router [class java.lang.Class]` and forced to to call its `getName()` in the target application code before returning to router.
* Change the `AbstractMappingMessageRouter` logic to treat `Class<?>` as a special String-aware case, use its `getName()` and don't go to the `ConversionService`
* Increase receive timeout for replies in the `TcpInboundGatewayTests`
a7dc7c3912