Incorrect validation message from /acme_accounts

[ocket8888]

This Bug Report affects these Traffic Control components:

• Traffic Ops

Current behavior:

If a PUT or POST request to /acme_accounts omits privateKey or makes it null or a blank string, the API will report in an error-level alert: "validating: 'private_key' cannot be blank"

Expected behavior:

The API should respond with the actual name of the missing, required field, which in this case is privateKey (not private_key).

Steps to reproduce:

topost -kpa 3.1 acme_accounts '{"email": "a", "uri": "a", "provider": "a"}'