Specifying No Default Value
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When redeclaring a property, you can specify that the property has no default value, even if the inherited property specified one.
To designate a property as having no default value, append the nodefault directive to the property's declaration. For example:
property FavoriteFlavor string nodefault;
__property int NewInteger = {nodefault};
When you declare a property for the first time, there is no need to include nodefault. The absence of a declared default value means that there is no default.