/// <summary>Constructor.</summary>
 /// <param name="manager">The QueryResultFilterManager.</param>
 /// <param name="filter">The filter predicate.</param>
 public QueryResultFilter(QueryResultFilterManager manager, Func <T, bool> filter) : base(manager, typeof(T))
 {
     Filter = filter;
 }
 /// <summary>Constructor.</summary>
 /// <param name="manager">The manager.</param>
 /// <param name="elementType">Type of the element.</param>
 internal QueryResultFilter(QueryResultFilterManager manager, Type elementType)
 {
     _manager    = manager;
     ElementType = elementType;
 }