400 Bad Request on Alexa AddOrUpdateReport using JSON from documentation - alexa

Question

My issue is basically described in title but I'll add a little bit more details here.
I'm trying to proactively send an update report to Alexa's Event Hub for Smart Home skills, however this fails with a 400 Bad Request error, and this is what the server responds:
{
"header": {
"namespace": "System",
"name": "Exception",
"messageId": "a154410c-2364-4c5b-9028-accde5048e1e"
},
"payload": {
"code": "INVALID_REQUEST_EXCEPTION",
"description": "Event or endpoint is missing in the request."
}
}
I decided then to check if my request was wrong by sending the one that can be found on their documentation, and I'm getting the very same error.
This is the JSON copied from Amazon's documentation (I just replaced device metadata and the token):
{
"event": {
"header": {
"namespace": "Alexa.Discovery",
"name": "AddOrUpdateReport",
"payloadVersion": "3",
"messageId": "5f8a426e-01e4-4cc9-8b79-65f8bd0fd8a4"
},
"payload": {
"endpoints": [
{
"endpointId": "<unique ID of the endpoint>",
"manufacturerName": "Sample Manufacturer",
"description": "Smart Light by Sample Manufacturer",
"friendlyName": "Kitchen Light",
"additionalAttributes": {
"manufacturer" : "Sample Manufacturer",
"model" : "Sample Model",
"serialNumber": "<the serial number of the device>",
"firmwareVersion" : "<the firmware version of the device>",
"softwareVersion": "<the software version of the device>",
"customIdentifier": "<your custom identifier for the device>"
},
"displayCategories": [
"LIGHT"
],
"capabilities": [
{
"type": "AlexaInterface",
"interface": "Alexa.PowerController",
"version": "3",
"properties": {
"supported": [
{
"name": "powerState"
}
],
"proactivelyReported": true,
"retrievable": true
}
},
{
"type": "AlexaInterface",
"interface": "Alexa.BrightnessController",
"version": "3",
"properties": {
"supported": [
{
"name": "brightness"
}
],
"proactivelyReported": true,
"retrievable": true
}
}
],
"connections": [
],
"cookie": {
}
}
],
"scope": {
"type": "BearerToken",
"token": "access-token-from-Amazon"
}
}
}
}
What I don't understand is why it reports that event or endpoints are missing if they're clearly there and if this JSON is the one that they provide in their documentation.
Does anyone have this issue too?
EDIT: pasting my payload as requested.
{
"event": {
"header": {
"namespace": "Alexa.Discovery",
"name": "AddOrUpdateReport",
"payloadVersion": "3",
"messageId": "132137185729061389"
},
"payload": {
"endpoints": [
{
"endpointId": "Rmxvb2RTZW5zb3JfMDE=",
"friendlyName": "Flood sensor",
"description": "Flood sensor",
"manufacturerName": "MyCompany",
"displayCategories": [
"ACTIVITY_TRIGGER"
],
"cookie": {
"DeviceType": "FloodSensor"
},
"capabilities": [{
"interface": "Alexa",
"type": "AlexaInterface",
"version": "3"
},
{
"interface": "Alexa.EndpointHealth",
"type": "AlexaInterface",
"version": "3",
"properties": {
"supported": [{
"name": "connectivity"
}],
"proactivelyReported": true,
"retrievable": true
}
}
]
}
],
"scope": {
"type": "BearerToken",
"token": "<redacted>"
}
}
}
}