# Description
This keeps plugin custom values that have requested drop notification
around during the lifetime of a plugin call / stream by sending them to
a channel that gets persisted during the lifetime of the call.
Before this change, it was very likely that the drop notification would
be sent before the plugin ever had a chance to handle the value it
received.
Tests have been added to make sure this works - see the `custom_values`
plugin.
cc @ayax79
# User-Facing Changes
This is basically just a bugfix, just a slightly big one.
However, I did add an `as_mut_any()` function for custom values, to
avoid having to clone them. This is a breaking change.
