The SynchronizeTaxonMessage as well as the SynchronizeTaxonMessageHandler has
been refactored to support the synchronization of multiple independent taxon
entities. Previously only the root node could be synchronized, which resulted
in always synchronizing the complete tree structure.
Sulu\Bundle\SyliusConsumerBundle\Message\SynchronizeTaxonMessage renamed to Sulu\Bundle\SyliusConsumerBundle\Message\SynchronizeTaxonsMessage
Sulu\Bundle\SyliusConsumerBundle\Handler\SynchronizeTaxonMessageHandler renamed to Sulu\Bundle\SyliusConsumerBundle\Handler\SynchronizeTaxonsMessageHandler