static @NonNull ImmutableContextSet of(@NonNull String key, @NonNull String value) {
        return LuckPermsProvider.get().getContextManager().getContextSetFactory().immutableOf(key, value);
    }
Creates an {@link ImmutableContextSet} from a context pair.

@param key   the key
@param value the value
@return a new ImmutableContextSet containing one context pair
@throws NullPointerException if key or value is null
api/src/main/java/net/luckperms/api/context/ImmutableContextSet.java