IPotionType

Importing the package

It might be required for you to import the package if you encounter any issues (like casting an Array), so better be safe than sorry and add the import.
import crafttweaker.potions.IPotionType;

Getting an IPotionType object

You can get such an object through the use of the PotionType Bracket handler

<potiontype:minecraft:long_strength>;

ZenGetter

ZenMethods

Imitate the PotionType Bracket Handler

This method does the same as the PotionType Bracket Handler.

//fromString(String potiontype);
IPotionType.fromString("minecraft:mundane");