The RemoveRequestParameterGatewayFilterFactory class builds up a new URI once it removes the request parameter outlined in the filter config, however currently expects the remaining
request parameters to all be encoded and the are not.
When the request query params are determined, they are decoded in AbstractServerHttpRequest and are not subsequently encoded again before
the filter builds up the URI.
Currently when the remaining request parameters have a character which requires encoding, you get an "Invalid character ' ' for QUERY_PARAM"
error.
Co-authored-by: Alan Moffat <alan.moffat@ros.gov.uk>