class Depot
{
}

private final HashMap<Integer, Depot> depots;
depots = new HashMap<>();

public Depot[] getDepots()
{
    if (depots.values().isEmpty())
    {
        return (Depot[]) new Object[0]; ***
    }
    else
    {
        return depots.values().toArray(new Depot[depots.values().size()-1]);
    }
}

public Depot[] getDepots()
{
    if (depots.isEmpty())
    {
        return new Depot[0];
    }
    else
    {
        return depots.values().toArray(new Depot[depots.size()]);
    }
}