I think rest.binding.requestURI should contain a string or expression that results in a correct URL. Probably the syntax of your expression is a bit faulty.
What I'd do is create a string based variable and assing the URI to that. Corresponding to your URL I assume something like https://host:port/myResourcePath?q=12345
(I'm not sure what the curly brackets in your sample mean, looks like there went something wrong with your copying/pasting and editing the URL). The result of the assignment should be a valid URL that you could copy and paste into your browser. Base the rest.binding.requestURI property on that variable. You could paste the expression of the assignment directly in the the property. But I prefer to do it using a variable, because then the flowtrace will show the resulting value before actually invoking it. Helps in debugging.