Method containsKey

paper-api/src/main/java/co/aikar/util/LoadingMap.java:262–263

(@Nullable Object key)

    public boolean isEmpty() {return backingMap.isEmpty();}

    @Override
    public boolean containsKey(@Nullable Object key) {return backingMap.containsKey(key);}

    @Override
    public boolean containsValue(@Nullable Object value) {return backingMap.containsValue(value);}