Make merchant accessible in PlayerPurchaseEvent

[NoyException]

When using a custom merchant, it's common to want to know whether a recipe is just used by listening PlayerPurchaseEvent. However, if we couldn't know which merchant players are trading with, we can't reach that goal.

So I just simply add the approach.

[lynxplay]

Sounds sensible, however now we are kinda doubling the #getVillager method in the PlayerTradeEvent as #getMerchant yields the same.

It might be beneficial to mark the #getVillager method as obsolete, overide the #getMerchant method to yield an AbstractVillager in PlayerTradeEvent and then have #getVillager link to it.

[NoyException]

Sounds sensible, however now we are kinda doubling the #getVillager method in the PlayerTradeEvent as #getMerchant yields the same.

It might be beneficial to mark the #getVillager method as obsolete, overide the #getMerchant method to yield an AbstractVillager in PlayerTradeEvent and then have #getVillager link to it.

You're absolutely right! I have made the changes as you said.

[lynxplay]

Neither of the events should be using jetbrains null-annotations, they are using jspecify already so should be fine without NotNull

[NoyException]

Neither of the events should be using jetbrains null-annotations, they are using jspecify already so should be fine without NotNull

Sure! I've corrected those. Could you please review again?