Fix WorldGuard

[ghost]

Description

Adds method removed in Guava 26.0

Checklist:

• [x] I have reviewed my code thoroughly.
• [x] I have tested my code.
• [x] My changes generate no new warnings @Lucaskyy

[Sculas]

Thank you! Waiting for checks to complete and then I'll merge :)

Guess what, checks completed as soon as I clicked send. Merging!