Expected URI syntax includes an "#anchor", as documented here:
"A fragment identifier component is indicated by the presence of a number sign ("#") character and terminated by the end of the URI."
ServletRedirectResult's current implementation allows anchor fragments to be used only if there are no query parameters present for the RedirectResult. In this case, the location param can be specified for a ServletRedirectResult with a #anchor suffix. However this does not work when using query parameters. ServletActionRedirectResult does not support #anchor due to runtime discovery of the target URI based on the actionName, namespace, and method.
Anchor fragments should be generally supported in redirection.