infoblox_zone_auth not able to inherit ttl values

[martinrohrbach]

We recently started to use the 'infoblox_zone_auth' resource because we prefer using the terraform provider rather than scripting the infoblox API which we've done in the past.

However, we're missing a crucial thing for us: it doesn't seem to be possible to inherit the SOA values such as ttl which is what we are usually doing in our grid. Even iif we don't specify the e.g. soa_default_ttl, the default kicks in and the inheritance of the zone is overridden.

Would it be possible to enhance the functionality to optionally inherit those value from the grid?