Major Description
The HttpSM contains a cached version of the client request url to avoid re-generating strings repeatedly. The problem is that if a plugin caches the MLoc and MBuf they can modify the URL without the cached copy being updated. Unfortunantely, moving the dirty flag into UrlImpl would be incredibly messy, so I will propose that after api callouts are complete we mark the cached url as dirty. It seems like the only reasonable approach that has minimal performance impact while maintaining the caching.