NBMsgPack020: [MessagePackConverter] type must be compatible converter

MessagePackConverterAttribute should specify a type that derives from MessagePackConverter<T> where the type argument is the type the attribute is applied to.

Learn more about custom converters.

Example violations

[MessagePackConverter(typeof(MyTypeConverter))] // MyTypeConverter does not derive from the correct base type
public class MyType
{
}

public class MyTypeConverter
{
	public MyType Read(ref MessagePackReader reader, SerializationContext context) => throw new System.NotImplementedException();
	public void Write(ref MessagePackWriter writer, ref MyType value, SerializationContext context) => throw new System.NotImplementedException();
}

Resolution

Fix the converter type to derive from MessagePackConverter<T>.

[MessagePackConverter(typeof(MyTypeConverter)]
class MyType
{
}

public class MyTypeConverter : MessagePackConverter<MyType>
{
	public override MyType Read(ref MessagePackReader reader, SerializationContext context) => throw new System.NotImplementedException();
	public override void Write(ref MessagePackWriter writer, in MyType value, SerializationContext context) => throw new System.NotImplementedException();
}