deploy ova/ovf with vAppConfig propoerties

I was trying to deploy an ova/ovf image with vAppConfig properties and was using the "propertyMapping" option to feed the properties before image deploy. I dont see any errors but properties are also not getting set. Pls. let me know if im missing something .. Using vCenter 6.7

    mapping = []
    for k,v in property_mapping.items():
       mapping.append(vim.KeyValue(key=k, value=v))

vim.OvfManager.CreateImportSpecParams(entityName=name, propertyMapping=mapping)