other: 0.759
semantic: 0.691
network: 0.627
device: 0.620
performance: 0.598
permissions: 0.500
debug: 0.476
socket: 0.469
files: 0.447
boot: 0.431
graphic: 0.346
PID: 0.240
KVM: 0.237
vnc: 0.233

qapi: add support to default value for optional members
Additional information:
This is a proposal to the QAPI spec itself to have a simple way to express that
an absent member defaults to a value.