Add configurations and update packages

GerstITS.Examples.Api/Common/Configurations/Extensions/IConfigurationExtensions.cs

@@ -0,0 +1,29 @@
+using System;
+using System.Linq;
+using Microsoft.Extensions.Configuration;
+
+namespace GerstITS.Examples.Api.Configurations
+{
+    public static class IConfigurationExtensions
+    {
+        #region Methods
+
+        public static TEnum GetFlaggedEnum<TEnum>(this IConfiguration configuration, string key)
+            where TEnum : struct, IConvertible
+        {
+            ThrowsAnExceptionIfTypeIsNotAnEnumeration<TEnum>();
+
+            return (TEnum)(object)(configuration.GetSection(key)?
+                    .Get<TEnum[]>() ?? Enumerable.Empty<TEnum>())
+                .Sum(i => (int)(object)i);
+        }
+
+        private static void ThrowsAnExceptionIfTypeIsNotAnEnumeration<TEnum>() where TEnum : struct, IConvertible
+        {
+            if (!typeof(TEnum).IsEnum)
+                throw new InvalidOperationException($"{typeof(TEnum)} is not supported.");
+        }
+
+        #endregion
+    }
+}