Named Options inherit values from parent?

[matthiaslischka]

Description

Not sure if that is a bug or just not expected by me, but:
Nested options that I resolve by name have values from the parent set instead of nulls.

Reproduction Steps

Given appsettings like

{
    "MySettings": {
        "SomeValue": "foo1",
        "AnotherValue": "bar1",

        "AnotherMySettings": {
            "SomeValue": "foo2"
        }
    }
}

Register both configs - default and named:

.Configure<MySettings>(null, GetConfiguration().GetSection("MySettings"))
.Configure<MySettings>("AnotherMySettings", GetConfiguration().GetSection("MySettings:AnotherMySettings"))

Resolve AnotherMySettings:

public MyService(IOptionsSnapshot<MySettings> mySettings)
{
    _mySettings = mySettings.Get("AnotherMySettings");
}

Expected behavior

_mySettings.SomeValue = foo2
_mySettings.AnotherValue = null

Actual behavior

_mySettings.SomeValue = foo2
_mySettings.AnotherValue = bar1

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

Demo Project: https://github.com/matthiaslischka/NamedOptions/

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[KalleOlaviNiemitalo]

Related comment in the source code:

runtime/src/libraries/Microsoft.Extensions.Options/src/ConfigureNamedOptions.cs

Lines 100 to 109 in 02f99e5

	public virtual void Configure(string? name, TOptions options)
	{
	ThrowHelper.ThrowIfNull(options);
	// Null name is used to configure all named options.
	if (Name == null || name == Name)
	{
	Action?.Invoke(options, Dependency);
	}
	}

If you want to configure only the default options, I think you'll need to use Options.DefaultName rather than null; or omit the argument altogether.

However, if this is by design, then it seems worth mentioning in the OptionsConfigurationServiceCollectionExtensions.Configure documentation.

[KalleOlaviNiemitalo]

The behavior looks inconsistent in that, after the .Configure<MySettings>(null, GetConfiguration().GetSection("MySettings")) registration, IOptionsChangeTokenSource<TOptions>.Name will be Options.DefaultName rather than null, even though MySettings options with all names should be reloaded.

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