== Why is this an issue?

include::../description.adoc[]

=== Noncompliant code example

[source,csharp]
----
[Serializable]
public class Foo
{
    [OptionalField(VersionAdded = 2)]
    int optionalField = 5;    
}
----


=== Compliant solution

[source,csharp]
----
[Serializable]
public class Foo
{
    [OptionalField(VersionAdded = 2)]
    int optionalField = 5;

    [OnDeserializing]
    void OnDeserializing(StreamingContext context)
    {
	    optionalField = 5;
    }

    [OnDeserialized]
    void OnDeserialized(StreamingContext context)
    {
        // Set optionalField if dependent on other deserialized values.
    }
}
----


ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

include::../message.adoc[]

include::../highlighting.adoc[]

'''
== Comments And Links
(visible only on this page)

include::../comments-and-links.adoc[]

endif::env-github,rspecator-view[]