constraints.cs

    class GenericClass<T> where T : class
    {
        private T _genericField;
        public T genericProperty { get; set; }

        public GenericClass(T value)
        {
            _genericField = value;
        }

        public T genericMethod(T genericParameter)
        {
            this.genericProperty = genericParameter;
            Console.WriteLine("Parameter type: {0}, value: {1}", typeof(T).ToString(), genericParameter);
            Console.WriteLine("Return type: {0}, value: {1}", typeof(T).ToString(), this._genericField);

            return this._genericField;
        }
    }