Description

For my use case I have the following third party XSD (simplified) for which I generate an enum:

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:simpleType name="YesOrNoOrEmpty">
        <xs:restriction base="xs:string">
            <xs:enumeration value="y" />
            <xs:enumeration value="n" />
            <xs:enumeration value="" />
        </xs:restriction>
    </xs:simpleType>
</xs:schema>

I want the generated enum to be serializable in both XML and JSON, so I annotate the members with both XmlEnumAttribute as well as the new JsonStringEnumMemberNameAttribute from System.Text.Json v9-preview.

For XML this works fine, but with JSON I get an exception, because empty strings are not allowed. I assume this might have something to do with support for Flags enums? But for enums without FlagsAttribute this restriction should not apply.

Reproduction Steps

using System.Text.Json.Serialization;
using System.Xml.Serialization;

public enum YesOrNoOrEmpty
{
    [JsonStringEnumMemberName("y")]
    [XmlEnum("y")]
    Yes,

    [JsonStringEnumMemberName("n")]
    [XmlEnum("n")]
    No,

    [JsonStringEnumMemberName("")]
    [XmlEnum("")]
    Empty,
}

Expected behavior

JsonStringEnumConverter is able to serialize and deserialize enums where the string representation of one of the enum members is an empty string. This matches behaviour of System.Xml's XmlEnumAttribute, and EnumMemberAttribute which is used by Newtonsoft.Json.

Actual behavior

JsonStringEnumConverter (using EnumConverter internally) does a string.IsNullOrEmpty check and throws an InvalidOperationException: Enum type '{0}' uses unsupported identifier '{1}'. It must not be null, empty, or containing leading or trailing whitespace. Flags enums must additionally not contain commas.

Regression?

No response

Known Workarounds

Implementing a custom JsonConverter for enums

Configuration

No response

Other information

No response