COBCH1840 <type-name> does not implement set accessor for property <property-name> of abstract class <type-name>

In the following example, COBCH1840 ("'type b' does not implement set accessor for property 'PropG1' abstract class 'type a'") is returned:

       class-id a public abstract.
       property-id PropG1 string abstract.
       getter.
       setter.
       end property.
       end class.

       class-id b inherits type a.
       01 PropG1        string public property with no set override.
       end class.