POST interaction/v1/eventDefinitions creates an Event Definition but I cannot see the Event on a Journey

Question

I am attempting to post a new API Event that can be added to a Journey as an entry source.

I am able to make this call via Rest and see the new event when I open Entry Sources under Journey Builder. I am NOT, however, able to see this new source on a Journey so I cannot add it.

I was able to get an event to show by adding a sourceApplicationExtensionId to the POST body, BUT only the Id from an API Event that was created manually via Journey Builder-->Entry Sources-->New that I found thru a GET interaction/v1/eventDefinitions.

For instance, this works as expected:

{
    "type": "APIEvent",
    "name": "PMCNO",
    "description": "Attempt to create fromm Api",
    "mode": "Production",
    "eventDefinitionKey": "PmcNO-3CF1CBA3-6F3D-4AB9-95B1-0D8CC2D2944B",
    "dataExtensionId": "f5959669-183f-e711-b410-38eaa7142c91",
    "dataExtensionName": "Mike Data Extension",
    "iconUrl": "/events/images/customer.png",
    "sourceApplicationExtensionId": "7db1f972-f8b7-49b6-91b5-fa218e13953d",
    "arguments": {
        "serializedObjectType": 11,
        "criteria": "",
        "useHighWatermark": false,
        "eventDefinitionKey": "PmcNO-3CF1CBA3-6F3D-4AB9-95B1-0D8CC2D2944B",
        "dataExtensionId": "f5959669-183f-e711-b410-38eaa7142c91"
    },
    "metaData": {
        "criteriaDescription": "",
        "scheduleState": "No Schedule"
    },
    "isVisibleInPicker": true,
    "category": "Event"
}

Note the sourceApplicationExtensionId -- that is the Id on a manually created API Event.

This DOES NOT work (as in the Entry Source is created, but the Source does not show on a Journey):

{
    "type": "APIEvent",
    "name": "PMCOHYA",
    "description": "Attempt to create fromm Api",
    "mode": "Production",
    "eventDefinitionKey": "PmcYA-3CF1CBA3-6F3D-4AB9-95B1-0D8CC2D2944B",
    "dataExtensionId": "f5959669-183f-e711-b410-38eaa7142c91",
    "dataExtensionName": "Mike Data Extension",
    "iconUrl": "/events/images/customer.png",
    "sourceApplicationExtensionId": "e7703c10-06db-41cb-910c-cd78552c7b7b",
    "arguments": {
        "serializedObjectType": 11,
        "criteria": "",
        "useHighWatermark": false,
        "eventDefinitionKey": "PmcYA-3CF1CBA3-6F3D-4AB9-95B1-0D8CC2D2944B",
        "dataExtensionId": "f5959669-183f-e711-b410-38eaa7142c91"
    },
    "metaData": {
        "criteriaDescription": "",
        "scheduleState": "No Schedule"
    },
    "isVisibleInPicker": true,
    "category": "Event"
}

That sourceApplicationExtensionId is the Id of my test application created in AppCenter.

This also DOES NOT work (as in, the Entry Source is successfully created, but the Entry Source does show on a Journey):

{
    "type": "APIEvent",
    "name": "PMCOHYA",
    "description": "Attempt to create fromm Api",
    "mode": "Production",
    "eventDefinitionKey": "PmcYA-3CF1CBA3-6F3D-4AB9-95B1-0D8CC2D2944B",
    "dataExtensionId": "f5959669-183f-e711-b410-38eaa7142c91",
    "dataExtensionName": "Mike Data Extension",
    "iconUrl": "/events/images/customer.png",
    "arguments": {
        "serializedObjectType": 11,
        "criteria": "",
        "useHighWatermark": false,
        "eventDefinitionKey": "PmcYA-3CF1CBA3-6F3D-4AB9-95B1-0D8CC2D2944B",
        "dataExtensionId": "f5959669-183f-e711-b410-38eaa7142c91"
    },
    "metaData": {
        "criteriaDescription": "",
        "scheduleState": "No Schedule"
    },
    "isVisibleInPicker": true,
    "category": "Event"
}

The Dev docs (https://developer.salesforce.com/docs/atlas.en-us.mc-apis.meta/mc-apis/createEventDefinition.htm) claim this property is not needed, but I am seeing differently in my testing and I cannot quite determine what it should actually be in reference to my app or Marketing Cloud instance.

Answer 1

This seemed to work for me when trying to customise an API entry event for a specific journey with a specified DE...

First, used the Journey API ID to source the other ID details (sourceApplicationExtensionId & dataExtensionId) needed to POST a new Entry Event within the relative Journey setup - in order to get that, used this;

GET [PARAMS =] 
https://www.exacttargetapis.com/interaction/v1/eventDefinitions/key:{API Key of Journey}
Authorization : BEARER [Paste token from above call]
Content Type: application/json

Then pasted those retrieved ID's into the new Event Definition POST...

Host: https://www.exacttargetapis.com
POST /interaction/v1/eventDefinitions
Content-Type: application/json
Authorization: Bearer YOUR_ACCESS_TOKEN

    {
"type": "APIEvent",
"name": "JOURNEY ALM eBrochure UAT",
"description": "Contacts submitting an eBrochure",
"mode": "Production",
"eventDefinitionKey": "UATeBrochure",
"dataExtensionId": "12345678-9101-e11e-1234-15g16hw17ie18",
"dataExtensionName": "SUBSCRIBERS_ALM_eBrochure_UAT",
"sourceApplicationExtensionId": "1grijm13-2abc-3456-78z9-de1011fg124",
"iconUrl": "/events/images/icon_journeyBuilder-event-api-blue.svg",
"arguments": {
    "serializedObjectType": 11,
    "eventDefinitionKey": "UATeBrochure",
    "dataExtensionId": "12345678-9101-e11e-1234-15g16hw17ie18",
    "criteria": "",
    "useHighWatermark": false
    },
"metaData": {
    "scheduleState": "No Schedule",
    "criteriaDescription": ""
    },
"isVisibleInPicker": true,
"category": "Event"
}

Went into the journey and was able to select the the API Entry Event, BUT NOT ABLE to customise anything within it, such as changes that can be done in a standard New API Entry Event Data Extension or Name.