A number of resources outside of the JCA subsystem depend on TransactionIntegrationService. So that wiring should be done via capability, which will result in the requirement being expressed in the configuration model (i.e. the jca subsystem must be part of the config if those resources are used.)

The capability can also depend on the relevant TX subsystem capabilities (see WFLY-9587 and subtasks), which then creates a model requirement for the tx subsystem if jca is used.