[libvirt] can not create "qcow2" format volume by Java library.

hi，all, when I use Java library to create volume ,specified format "qcow2"，but when I check it use qemu-img info ,it show format is "raw".。 I think it a bug,can you fix it .. thanks very much. the java library version：0.4.8 libvirt version：0.9.8