XP related text was removed in EAP 7.4.beta from patching guide from chapters:

• 2.1.2. Applying a Patch
  • You can manage the JBoss EAP XP patches only using the management CLI. For information about JBoss EAP XP patch streams, see JBoss EAP XP manager for managing JBoss EAP XP patch streams in the Using Eclipse MicroProfile in JBoss EAP guide.
• 2.1.3. Rolling Back a Patch
  • You can manage the JBoss EAP XP patches only using the management CLI. For information about JBoss EAP XP patch streams, see JBoss EAP XP manager for managing JBoss EAP XP patch streams in the Using Eclipse MicroProfile in JBoss EAP guide.

It's not clear whether XP will be still supported for EAP 7.4. But there is a chance that yes. This needs to be checked before GA and if XP will be supported, related text should be added to patching guide (if these text will be still valid for new XP).