I had assumed that a filter should not expect to outlive the factory lambda that created it, so it should receive its config objects via a shared_ptr, e.g.:

https://github.com/envoyproxy/envoy/blob/master/source/extensions/filters/http/header_to_metadata/config.cc#L24

And that's pretty much true for all filters, except for this one:

https://github.com/envoyproxy/envoy/blob/master/source/extensions/filters/http/original_src/original_src_config_factory.cc#L19

Is it OK then for filters to assume their creator will outlive them (and thus can we ditch shared_ptrs and pass refs instead)? Would be nice to have some consistency there (PRs to follow, if we agree).

cc: @mattklein123 @jparise @derekargueta