I think this is what you are looking for in Java:
this.addRefreshClass("Module.Object");
eg. this.addRefreshClass("VragenlijstCuratief.VraagGebruiker");
When you enable the "Refresh in client" option of a Create Object or Delete Object activity that operates on your object type, it will generate a 'class refresh' in the client, which will refresh datagrids showing objects of that type. If you have no Create or Delete activity in your microflow yet, as a workaround you could create and then delete an object to trigger this behavior.