JSON plan output data missing?

Hi All,

I am experimenting with using the JSON representation of terraform plans and wanted to confirm something.

I have noticed if there is a nested structure such as this in the plan output
ebs_block_device {
+ delete_on_termination = (known after apply)
+ device_name = (known after apply)
+ encrypted = (known after apply)
+ iops = (known after apply)
+ kms_key_id = (known after apply)
+ snapshot_id = (known after apply)
+ volume_id = (known after apply)
+ volume_size = (known after apply)
+ volume_type = (known after apply)
}

The JSON does not include the inner keys such as delete_on_termination etc The only reference is in the after_unknown section of the json

"ebs_block_device": true,

If all of the internal values of an object are unknown are they simply omitted from the JSON ?
I note this comment in https://www.terraform.io/docs/internals/json-format.html#change-representation

" The after value will be incomplete if there are values within it that won’t be known until after apply"

but that page doesn’t reference the unknown section of JSON specifically.

Any guidance much appreciated.