With the introduction of set_defaults, as well as new documentation
features for default values in oslo_config, the CORS middleware
has been placed in the odd position where its configuration behaves
inconsistently. If you configure via add_origin, then defaults set
in set_defaults are not honored. If you configure via multiple
configuration blocks ([cors.foo]), then the defaults are also not
honored.
Additionally, with the conversion of allowed_origin into a list_opt,
there is less direct need for multiple config-block parsing.
In order to ensure that the middleware behaves consistently with
the rest of oslo, as well as adheres to a set of basic sane assumptions
made by consumers, this patch deprecates the code path that searches
oslo's configuration for multiple [cors.*] blocks. Subsequent patches
will add additional deprecation flags to this end.
Change-Id: I49c15ccc2dce03b0dea33ec45ef6e271e58582da
399e94043f