Set up the syncing of many to many foreign keys.
@example Set up the syncing.
Person.synced(metadata)
@param [ Metadata ] metadata The relation metadata.
@since 2.1.0
# File lib/mongoid/relations/synchronization.rb, line 112 def synced(metadata) unless metadata.forced_nil_inverse? synced_save(metadata) synced_destroy(metadata) end end