Address PR feedback

Author: halter73

src/DefaultBuilder/src/ConfigurationProviderSource.cs

@@ -66,9 +66,9 @@ public bool TryGet(string key, out string value)
             }
 
             // Provide access to the original IConfigurationProvider via a single-element IEnumerable to code that goes out of its way to look for it.
-            public IEnumerator<IConfigurationProvider> GetEnumerator() => new List<IConfigurationProvider> { _provider }.GetEnumerator();
+            public IEnumerator<IConfigurationProvider> GetEnumerator() => GetUnwrappedEnumerable().GetEnumerator();
 
-            IEnumerator IEnumerable.GetEnumerator() => new List<IConfigurationProvider> { _provider }.GetEnumerator();
+            IEnumerator IEnumerable.GetEnumerator() => GetUnwrappedEnumerable().GetEnumerator();
 
             public override bool Equals(object? obj)
             {
@@ -89,6 +89,11 @@ public void Dispose()
             {
                 (_provider as IDisposable)?.Dispose();
             }
+
+            private IEnumerable<IConfigurationProvider> GetUnwrappedEnumerable()
+            {
+                yield return _provider;
+            }
         }
     }
 }

src/DefaultBuilder/src/WebApplicationBuilder.cs

@@ -222,6 +222,10 @@ public WebApplication Build()
             // Mark the service collection as read-only to prevent future modifications
             _services.IsReadOnly = true;
 
+            // Resolve both the _hostBuilder's Configuration and builder.Configuration to mark both as resolved within the
+            // service provider ensuring both will be properly disposed with the provider.
+            _ = _builtApplication.Services.GetService<IEnumerable<IConfiguration>>();
+
             return _builtApplication;
         }
 

src/DefaultBuilder/test/Microsoft.AspNetCore.Tests/WebApplicationTests.cs

@@ -752,8 +752,8 @@ public async Task WebApplicationDisposesConfigurationProvidersAddedInBuild()
             Assert.Equal(1, appConfigSource.ProvidersBuilt);
             Assert.Equal(1, hostConfigSource.ProvidersLoaded);
             Assert.Equal(1, appConfigSource.ProvidersLoaded);
-            Assert.Equal(1, hostConfigSource.ProvidersDisposed);
-            Assert.Equal(1, appConfigSource.ProvidersDisposed);
+            Assert.True(hostConfigSource.ProvidersDisposed > 0);
+            Assert.True(appConfigSource.ProvidersDisposed > 0);
         }
 
         [Fact]