平面化xml以进行反序列化

我要反序列化xml，为此我使用了这些类

[DataContract(Name = "Validation")]
public class FieldValidationModel
{
    [DataMember]
    public string Annotation { get; set; }
    [DataMember]
    public Collection<ValidationPlanType> PlanTypes { get; set; }
}
[DataContract(Name="PlanType")]
public class ValidationPlanType
{
    [DataMember]
    public string Name { get; set; }
}

它可以工作，但理想情况下我希望只使用一个类

[DataContract(Name = "Validation")]
public class FieldValidationModel
{
    [DataMember]
    public string Annotation { get; set; }
    [DataMember]
    public List<string> PlanTypes { get; set; }
} 

我已经尝试使用

[DataMember]
[XmlArray, XmlArrayItem(Namespace="PlanType")]
public List<string> PlanTypes { get; set; }

没有运气，如果我可以这样做的话，节点将会被我现在使用的平坦

<Validation>
  <Annotation>TestAnnotation</Annotation>
  <PlanTypes>
    <PlanType>
      <Name>PlanA</Name>
    </PlanType>
    <PlanType>
      <Name>PlanB</Name>
    </PlanType>
  </PlanTypes>
</Validation>

到更可读的

<Validation>
  <Annotation>TestAnnotation</Annotation>
  <PlanTypes>
    <PlanType>PlanA</PlanType>
    <PlanType>PlanB</PlanType>
  </PlanTypes>
</Validation>

谢谢

[DataContract(Name = "Validation")]
public class FieldValidationModel
{
      [DataMember]
      public string Annotation { get; set; }
      [DataMember]
      public PlanTypeCollection PlanTypes { get; set; }
}
[CollectionDataContract(ItemName="PlanType")]
public class PlanTypeCollection : Collection<string>  {}