[release/8.0-preview6] [Blazor] Allow properties marked with both [Parameter] and [SupplyParameterFromQuery] to receive values directly

[MackinnonBuck]

Allow properties marked with both [Parameter] and [SupplyParameterFromQuery] to receive values directly

Fixes an issue where if a component parameter was marked with both [Parameter] and [SupplyParameterFromQuery], a misleading exception message would be thrown when the parameter's value was set directly.

Backport of #48954

Description

Since #48554 was merged, marking a component parameter with both [Parameter] and [SupplyParameterFromQuery] would cause the following exception to be thrown if the parameter was set directly:

Object of type 'MyComponent' has a property matching the name 'MyParameter', but it does not have [ParameterAttribute] applied.

This is a breaking change because prior to the recent changes, component parameters annotated with both attributes could receive values directly without throwing an exception.

This PR fixes the issue by allowing [Parameter] and [SupplyParameterFromQuery] to both exist on a single property without causing an exception to be thrown. If both direct and cascading parameter values are supplied, the direct parameter value is preferred.

Fixes #48937

Customer Impact

Moderate. It's somewhat uncommon to need to do this, but the original issue report did mention a component library that was impacted by this change.

Regression?

• Yes
• No

Regressed from .NET 8.0 Preview 5

Risk

• High
• Medium
• Low

This is a straightforward change in a well-tested area, and new tests have been added to verify that the fix works correctly.

Verification

• Manual (required)
• Automated

Packaging changes reviewed?

• Yes
• No
• N/A

[ghost]

Hi @MackinnonBuck. Please make sure you've updated the PR description to use the Shiproom Template. Also, make sure this PR is not marked as a draft and is ready-to-merge.

To learn more about how to prepare a servicing PR click here.

[ghost]

Hi @MackinnonBuck. This PR was just approved to be included in the upcoming servicing release. Somebody from the @dotnet/aspnet-build team will get it merged when the branches are open. Until then, please make sure all the CI checks pass and the PR is reviewed.

[mkArtakMSFT]

Thanks @MackinnonBuck.
Approved based on the earlier approval of the original PR.