PropertyHandle :: SetType - Set type for weak-typed collection

Before creating a new instance for a weak-typed collection the type of the instance to be inserted has to be set in the property handle. The type of instance to be created is passed as structure name (strnames). This setting might be reset when reading the next instance in the collection.

When the type name passed (strnames) has a shared base type, a warning is written zu the error log-file, since this may cause problems later on..