Guideline: A collection such as List<Integer> can be mapped to a list of XML values (that is, an XML schema list simple type) using annotation @XmlList. .NET maps a list simple type to a .NET System.string.
Example: Collection to a list of values using @XmlList
//-- Java code fragment @XmlRootElement(name="po") public PurchaseOrder { @XmlList public List<Integer> items; } //-- Schema fragment <xs:element name="po" type="purchaseOrder"> <xs:complexType name="purchaseOrder"> <xs:element name="items" minOccurs="0"> <xs:simpleType> <xs:list itemType="xs:int"/> </xs:simpleType> </xs:element> </xs:complexType> ... //-- XML serialization <po> <items> 1 2 3 </items> </po> // .NET auto generated code from schema partial class purchaseOrder { private string itemsField; public string items { get { return this.itemsField; } set { this.itemsField = value; } } }