Spring Cloud Gateway - RewritePath not keeping # (URI fragment)

Question

I'm working with Spring Cloud Gateway (Hoxton.SR6 version) and Java 11, and I have problems redirecting urls containing a "#" :

For example '{host}/api/v1/foo#bar' is redirected to /foo, while I would like to keep the '#bar' part too.

Here is my configuration:

  routes:
        - id: apiId
          uri: https://foo.free.beeceptor.com
          predicates:
            - Path=/api/v1/**
          filters:
            - RewritePath=/api/v1/(?<segment>/?.*), /$\{segment}

However when I test the regex, the "#" character is supposed to stay :
screenshot regex101

Edit : In fact the problem does not come from the RewritePath filter, but before : When the request arrives, the "uri fragments" are already deleted ... I'll keep looking