$ curl -s -X POST localhost:8080/contact-record \
     -H 'Content-Type: application/json' -H 'Accept: application/json' \
     -d '{"email":"spammy@email.com","message":"This is spam."}'

HTTP status: 400
Content-Type: null
Body: '' (still empty!)

# An Accept header alone changes nothing -- the body is still empty. What actually turns
# on a structured error body is the spring.mvc.problemdetails.enabled property, which is
# off by default and unrelated to content negotiation. See
# docs/output/07-problemdetails-enabled-record-rejected.txt for the same request with it on.