Webhook JSON packets - reverse order for Custom

When selecting “Custom” JSON data in Webhook builder Advanced Settings, the received order of JSON objects is reversed. The Integration is generated from within a Particle “Product”. Request Type POST / Request Format JSON. For testing, I’m sending data to requestbin.com. Here is the received data for “Custom” case:

{
“public”: “false”,
“fw_version”: “0”,
“userid”: “”,
“published_at”: “2019-10-01T14:47:40.510Z”,
“coreid”: “”,
“data”: “{“t1”: “227.68”, “t2”: “173.29”, “p1”: “6.37”, “l1”: “19.00”}”,
“event”: “sensors”
}

When I changed back to “Default” setting, the order returned to expected:

{
“event”: “sensors”,
“data”: “{“t1”: “164.15”, “t2”: “206.23”, “p1”: “29.36”, “l1”: “43.98”}”,
“published_at”: “2019-10-01T14:51:40.507Z”,
“coreid”: “”,
“userid”: “”,
“fw_version”: 0,
“public”: false
}

In both cases, the integration has:
{
“event”: “{{{PARTICLE_EVENT_NAME}}}”,
“data”: “{{{PARTICLE_EVENT_VALUE}}}”,
“coreid”: “{{{PARTICLE_DEVICE_ID}}}”,
“published_at”: “{{{PARTICLE_PUBLISHED_AT}}}”,
“userid”: “{{{PRODUCT_USER_ID}}}”,
“fw_version”: “{{{PRODUCT_VERSION}}}”,
“public”: “{{{PARTICLE_EVENT_PUBLIC}}}”
}

Is this expected behavior for “Custom”?