1. Fields that are mandatory, but we do not support them:

• nat/instances/instance/connection-limits/limit-per-instance
• nat/instances/instance/policy/port-set/port-set-size
  this one might be ODL missing feature, because port-set is defined using when statement:

container port-set {
    when "../port-allocation-type = 'port-range-allocation'";
    [...]
}

2. Check if ip-prefix or ip-address should be used

Examples in the https://tools.ietf.org/html/draft-ietf-opsawg-nat-yang-14
use ip-address, but YANG definitions ip-prefix.