this.array = (X[]) Array.newInstance(init.getClass(), size);

// ...

public List<X> get()  {
    return Collections.<X>unmodifiableList(this.array);
}

public List<X> get()  {
    return Collections.unmodifiableList(new ArrayList<>(this.array));
}

public List<X> get()  {
    return Arrays.asList(this.array);
}

public List<X> get()
{
    List<X> modifiableList = Arrays.asList( this.array );
    return Collections.unmodifiableList( modifiableList );
}