<XmlElementAttribute(True)>
Public Property whatId As String

Dim instance As SingleEmailMessage
Dim value As String
 
instance.whatId = value
 
value = instance.whatId

[XmlElementAttribute(true)]
public string whatId {get; set;}

[XmlElementAttribute(true)]
public: __property string* get_whatId();
public: __property void set_whatId( 
   string* value
);

[XmlElementAttribute(true)]
public:
property String^ whatId {
   String^ get();
   void set (    String^ value);
}