I am using article get using REST calls. But I do not get field groups in the JSON.

"fields":[
{
"id":"1",
"title":"Non-English",
"name":"non-english",
"type":"textarea",
"default_value":"",
"group_id":"0",
"label":"Non-English",
"description":"",
"required":"1",
"value":"Non-English field",
"rawvalue":"Non-English field"
},
{
"id":"2",
"title":"Lang",
"name":"lang",
"type":"integer",
"default_value":"",
"group_id":"1",
"label":"Lang",
"description":"",
"required":"0",
"value":"22",
"rawvalue":"22"
}
],


jBackend Version 3.5.0

Setting Value
PHP Built On Linux s053.panelboxmanager.com 2.6.32-531.17.1.lve1.2.60.el6.x86_64 #1 SMP Tue Jul 8 11:25:32 EDT 2014 x86_64
Database Version 5.5.56-MariaDB-cll-lve
Database Collation utf8_general_ci
Database Connection Collation utf8mb4_general_ci
PHP Version 7.0.23
Web Server Apache
WebServer to PHP Interface cgi-fcgi
Joomla! Version Joomla! 3.7.5 Stable [ Amani ] 14-August-2017 12:09 GMT
Joomla! Platform Version Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT
User Agent Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:55.0) Gecko/20100101 Firefox/55.0