COBCH1790 Illegal use of 'void' type

The type java.lang.void cannot be used as a data type or parameter type, etc. The only context in which these void types are allowed is in a TYPE OF phrase.

       class-id a.
       01 v1 type System.Void.                    *> This line causes an error
       01 t1 object value type of System.Void.    *> This line does not
       end class.