RewriteRule .* ${portals:%{HTTP_HOST}} Gives in catalin.oput startup file: Caused by: java.lang.IllegalArgumentException: %{HTTP_HOST portals is a rewritemap type and we have tested that it works if we replace the %{HTTP_HOST} variable with a hardcoded value, it works correct. Comment: curly braces nesting looks to be a bit more difficult, it is possible it will not get done.
The implementation for these sort of nesting will be in 9.0.13 and 8.5.35 along with a test case.