Handle YANG type of empty within Telegraf

[remingtonc]

For some fields they may have a type of empty. These fields do not necessarily have a value, and are represented that way in MDT. Need to determine how to treat - a boolean? What should the default behavior be? Current example is IOS XE interface shutdown leaf - this leaf will simply be present when the state changes. Would need to track each shutdown toggle? If in MDT the field has a name, and now fields, and no *value, then treat as empty?

INFO:root:node_id_str: "blahblah"
subscription_id_str: "106"
encoding_path: "Cisco-IOS-XE-native:native"
msg_timestamp: 1594323085718
data_gpbkv {
  timestamp: 1594323085718
  fields {
    name: "keys"
  }
  fields {
    name: "content"
    fields {
      name: "interface"
      fields {
        name: "GigabitEthernet"
        fields {
          name: "name"
          string_value: "1"
        }
        fields {
          name: "shutdown"
        }
      }
    }
  }
}

[remingtonc]

To handle, should start with:

1. Simply emit a value, like 0.
2. Track XPaths and toggle?