The PortalSpawn Event is fired when an attempt is made to spawn a nether portal. If cancelled, the portal will not be spawned.

You will need to cast the event in the function header as this class:
crafttweaker.event.PortalSpawnEvent
You can, of course, also import the class before and use that name then.

Erweiterte Event-Schnittellen

Link to erweiterte-event-schnittellen

BlockNeighborNotify Events implement the following interfaces and are able to call all of their methods/getters/setters as well:

ZenGetterTypeBeschreibung
ZenGetter
valid
Type
bool
Beschreibung
If the size of portal is valid
ZenGetter
height
Type
int
Beschreibung
The height of portal
ZenGetter
width
Type
int
Beschreibung
The width of portal