Add project files.

src/framework/Elsa.Studio.Shared/Extensions/ClaimsExtensions.cs

@@ -0,0 +1,20 @@
+using System.Security.Claims;
+
+namespace Elsa.Studio.Extensions;
+
+/// <summary>
+/// Contains extension methods for <see cref="IEnumerable{Claim}" />.
+/// </summary>
+public static class ClaimsExtensions
+{
+    /// <summary>
+    /// Determines whether the "exp" claim is expired.
+    /// </summary>
+    public static bool IsExpired(this IEnumerable<Claim> claims)
+    {
+        var expString = claims.FirstOrDefault(x => x.Type == "exp")?.Value.Trim();
+        var exp = !string.IsNullOrEmpty(expString) ? long.Parse(expString) : 0;
+        var expiresAt = DateTimeOffset.FromUnixTimeSeconds(exp);
+        return expiresAt < DateTimeOffset.UtcNow;
+    }
+}