/// <summary>Update the space/namespace/type usage of the tree</summary>
/// <param name="delta">the change of the namespace/space/type usage</param>
public void AddSpaceConsumed2Cache(QuotaCounts delta)
{
usage.Add(delta);
}
/// <summary>Add current quota usage to counts and return the updated counts</summary>
/// <param name="counts">counts to be added with current quota usage</param>
/// <returns>counts that have been added with the current qutoa usage</returns>
internal QuotaCounts AddCurrentSpaceUsage(QuotaCounts counts)
{
counts.Add(this.usage);
return(counts);
}