A loaded peas.PluginInfo
The implemented extension GType
the name of the first property.
the value of the first property, followed optionally by more name/value pairs, followed by NULL.
a new instance of PeasExtension wrapping the extension_type instance, or NULL.
If the plugin identified by info implements the extension_type, then this function will return a new instance of this implementation, wrapped in a new PeasExtension instance. Otherwise, it will return NULL.
Since libpeas 1.22, extension_type can be an Abstract GType and not just an Interface GType
See Engine.createExtension for more information.