External Reference for Web Services

This add-on extends the Znuny Generic Interface with the 'Ticket::ExternalReference' operation. It enables external systems (such as Jira, Salesforce, or ERP solutions) to interact with Znuny tickets using their own reference IDs. When a request is received, the system automatically checks if a ticket with that external reference already exists. If found, the ticket is updated; otherwise, a new ticket is created. This prevents duplicate tickets and significantly simplifies integration, as the external system does not need to store or manage Znuny-specific ticket IDs. The logic can be fine-tuned to update only tickets in specific states or to force the creation of a new ticket if the previous one is already closed.