Description

XmlElement's constructor should have a nullable prefix parameter. It's declared as:

 protected internal XmlElement(string prefix, string localName, string? namespaceURI, XmlDocument doc)
        : this(doc.AddXmlName(prefix, localName, namespaceURI, null), true, doc)

prefix should be nullable. There are derived classes that have nullable prefixes and they should be able to pass a nullable prefix down to this constructor.

Also, the very first usage of prefix is in doc.AddXmlName which is declared as: internal XmlName AddXmlName(string? prefix, ...

Reproduction Steps

No particular reproduction steps.

Expected behavior

The parameter should be nullable so that derived classes with nullable prefixes can work properly with this constructor.

Actual behavior

Derived classes have to workaround nullability, either by supressing nullable errors, or by using a ! to force non-null.

Regression?

I would say not. No behaviour was changed when annotating this constructor.

Known Workarounds

Derived classes needing this constructor can add damin operators on this parameter, but it needs fixing.

Configuration

No response

Other information

No response