The book specifies on page 104 (PDF-version) that one must make a request with method PUT and ‘long: What The Fudge’ as the JSON body. That will return a 400 Bad Request, requiring a value for key ‘short’. So the correct request here would be:
Update Acronym
Endpoint: PUT - http://localhost:9090/api/acronyms/4
Header
{
Content-Type: application/json; charset=utf-8
}
Body
{
"short": "What The Fudge",
"long": "WTF"
}