If you want to inject `Map<String, Expression>` at runtime it just enough to do this:
`HttpRequestExecutingMessageHandler#setUriVariableExpressions`
e.g.:
`<int:outbound-channel-adapter channel="controlBus" expression="@'httpOutbound.handler'.uriVariableExpressions = @uriVariables"/>`
Of course, in this case we should make `httpOutbound` endpoint single-threaded - wrap its `handleRequestMessage` with `LockAdvice`.
Anyway I can check the result of `uriVariablesExpression` evaluation and wrap it to `ExpressionEvalMap`