Meaning of curly braces after the "is" operator
Solution 1:
This is a new pattern matching feature which was introduced in C# 8.0 and is called property pattern. In this particular case it is used to check that object is not null, example from linked article:
static string Display(object o) => o switch
{
Point { X: 0, Y: 0 } p => "origin",
Point { X: var x, Y: var y } p => $"({x}, {y})",
{} => o.ToString(),
null => "null"
};