GET will give you description of the service operation; it won't execute it.
If you must use GET, you'll need a middle-tier service that accepts a GET request and makes a POST request to F&O. Azure API Management might be a good choice.
By the way, use Insert > Insert Code (in the rich formatting view) to paste source code. In this particular case, you can also benefit from the fact that it supports JSON language. It even highlights a syntax error in the second snippet.
GET
{
"Parameters": [],
"Return": {
"Name": "return",
"Type": "ListValueContract"
}
}
POST
{
"$id": "1",
"ListProject": [
{
"$id": "2",
"ProjectId": "P001",
"ProjectDesc": "Non Project",
"ProjectDataArea": "bb",
"ErpId": 5637146101
}
}
