AL0009: Don't call IXmlSerializable.GetSchema

Calling GetSchema is not supported; it should always return null and isn't intended to be invoked.

When it triggers

IXmlSerializable serializable = GetSerializable();

// AL0009: Don't call IXmlSerializable.GetSchema
var schema = serializable.GetSchema();

Why this matters

The GetSchema method in IXmlSerializable is a historical artifact. It should always return null and isn't meant to be called. Schema information should be retrieved via XmlSchemaProviderAttribute instead.

How to fix

Remove the call and use proper schema discovery mechanisms:

// Use XmlSchemaProviderAttribute on your type for schema information
[XmlSchemaProvider("GetMySchema")]
public class MySerializable : IXmlSerializable
{
    public static XmlQualifiedName GetMySchema(XmlSchemaSet schemas)
    {
        // Return schema information here
    }
}

Configuration

[*.cs]
dotnet_diagnostic.AL0009.severity = warning