I've been searching for days on this problem
This is my solution:
Var A
"
-H \"Authorization: Bearer d38ed55f65690b37b6f2db4329009e7221f80617e77029ce465b079eb390a893\"
" & "
-H \"Accept-version: 1.0.0\"
" & "
-H \"Content-Type: application/json\"
" & "
-X POST \ "
Var B (type your Json in a field and use a calculation to end up with a variable)
JsonFormatElements
Var C
"--data @$varB"
Insert from URL
cURL options: varA & varC