| Overload | Description |
|---|---|
| GetAdditionalProperty(String) | Returns the property with the specified name, or a null reference (Nothing in Visual Basic) if the property does not exist. |
| GetAdditionalProperty(String,String) | Returns the property with the specified name, or the defaultValue if the property is not defined for this message. |
| GetAdditionalProperty(String,Int32) | Returns the property with the specified name, or the defaultValue if the property is not defined for this message. |