Why does curl sends data in post as {data=}? - linux

Question

I was coding a simple rest service in Apache Camel, and testing it using the curl command by invoking the endpoint of my service.
The service receives in plain text a simple String like "ABC123-D-FE", but as I made multiple tests, the data was always received as "{ABC123-D-FE=}", always adding the "{ =}".
At first I thought it was my service catching the data like that, but every other method I tried (i.e. rest clients, postman, invoking the service by other services) never reproduced that results, and the service always received just the plain text data.
It was only formatted like that by using curl.
The command was:
curl -X POST -d ABC123-F-DE http://host/service
Can't find any reference to this behaviour, and the only conclusion is something curl does by default (and don't understand why or how to remove it).
I was using the curl command in Ubuntu Mate 20.04.

Answer 1

Edit: per Nick ODell's comment below, it almost certainly means it's parsed to a map with the key "ABC123-F-DE" having an empty value, like this json:
{
"ABC123-F-DE": ""
}
i guess it's your parsed-object-stringify function adding the { to signify start of map, and adding the = to specify "value of this key" and adding } to specify end of map?
lets check what curl actually sends with a little netcat server:
$ nc -l 1111
followed by
$ curl -X POST -d ABC123-F-DE http://localhost:1111
yields:
$ nc -l 1111
POST / HTTP/1.1
Host: localhost:1111
User-Agent: curl/7.84.0
Accept: */*
Content-Length: 11
Content-Type: application/x-www-form-urlencoded
ABC123-F-DE
Conclusion: it's definitely not curl.
My best guess: it's something weird with your server's application/x-www-form-urlencoded-parser?