/// <summary>
        /// Finds users whose properties have certain values.
        /// </summary>
        /// <param name="propValues">Properties and values to look for.</param>
        /// <param name="props">Properties that will be requested by the engine from the returned users.</param>
        /// <returns>Enumerable with users whose properties match.</returns>
        public IEnumerable<IPrincipal> FindPrincipalsByPropertyValues(
            IList<PropertyValue> propValues,
            IList<PropertyName> props)
        {
            var user = new UserPrincipal(Context.GetPrincipalContext());
            user.Name = "*";
            foreach (PropertyValue v in propValues)
            {
                if (v.QualifiedName == PropertyName.DISPLAYNAME)
                {
                    user.Name = "*" + v.Value + "*";
                }
            }

            var searcher = new PrincipalSearcher(user);
            return searcher.FindAll().Select(u => new User((UserPrincipal)u, Context)).Cast<IPrincipal>();
        }