Microsoft Graph translateExchangeIds not returning the same id as EWS - microsoft-graph-api

Question

I am working with both EWS and the Graph API.
I would like to create events (online meetings with skype/teams) in an calendar that is already available via EWS.
To match the calendar to the one available via Graph API i try to use https://learn.microsoft.com/en-us/graph/api/user-translateexchangeids
The calendar i created has this id when returned by the FindFolder call:
<t:FolderId Id="AAMkAGNiY2YxMjY3LTUxYjgtNGI1Yy1hOTM2LTU4MTM5OTZiNjdjYgAuAAAAAABW2gY0kRG1SqggDTNZN6i8AQAPJkKZ1XJkQ6huFmcVa6XaAAGixNZ3AAA=" ChangeKey="..."/>
<t:DisplayName>Test</t:DisplayName>
I create a request to the graph api:
{
"inputIds": [
"AAMkAGNiY2YxMjY3LTUxYjgtNGI1Yy1hOTM2LTU4MTM5OTZiNjdjYgAuAAAAAABW2gY0kRG1SqggDTNZN6i8AQAPJkKZ1XJkQ6huFmcVa6XaAAGixNZ3AAA="
],
"sourceIdType": "ewsId",
"targetIdType": "restId"}
and get the result
{
"#odata.context": "https://graph.microsoft.com/v1.0/$metadata#Collection(microsoft.graph.convertIdResult)",
"value": [
{
"sourceId": "AAMkAGNiY2YxMjY3LTUxYjgtNGI1Yy1hOTM2LTU4MTM5OTZiNjdjYgAuAAAAAABW2gY0kRG1SqggDTNZN6i8AQAPJkKZ1XJkQ6huFmcVa6XaAAGixNZ3AAA=",
"targetId": "AAMkAGNiY2YxMjY3LTUxYjgtNGI1Yy1hOTM2LTU4MTM5OTZiNjdjYgAuAAAAAABW2gY0kRG1SqggDTNZN6i8AQAPJkKZ1XJkQ6huFmcVa6XaAAGixNZ3AAA="
}
]
}
However, if i call https://graph.microsoft.com/v1.0/me/calendars i get a different id
"id": "AAMkAGNiY2YxMjY3LTUxYjgtNGI1Yy1hOTM2LTU4MTM5OTZiNjdjYgBGAAAAAABW2gY0kRG1SqggDTNZN6i8BwBIq5JjIBY-RqWQllrF0GSkAAAAB353AAAPJkKZ1XJkQ6huFmcVa6XaAAGixNowAAA=",
"name": "Test",
Is there a way to match the (ews) calendar i already have to the one returned by the Graph API?

Answer 1

This is a shot in the dark, because I've never dug this deeply into the weeds on the Graph Ids, but you might try calling Graph with the header that selects "immutable ids." I tried to find some details on what this actually means without much luck.
The header is:
request.Header("Prefer", "IdType=\"ImmutableId\"");
HTH, and if not, sorry for guessing.