I am currently experimenting with capabilities and don't know if getting my capability this way:

// PARTY_CAP is my Capability<T> object.
player.getCapability(PartyProvider.PARTY_CAP).orElse(PartyProvider.PARTY_CAP.getDefaultInstance());

is correct, or if it's not intended to be get that way.

Depends on what you want to do with it.

But no, this probably won't do what you really want. If the player doesn't have the capability, you're going to get a blank one, make some changes to it, then toss it in the garbage.

 

It is better to use ifPresent, which takes in a lambda operator. But in general:

Capability cap = player.GetCapability(...).orElse(null);
if(cap != null) {
    //do stuff
}

is the same as 

player.GetCapability(...).ifPresent(cap -> {
    //do stuff
});