how to set the default flag on item class template

Summary:

I am using the Item Class Template REST web serivce to update/import item class templates but we seem to be missing the Default flag on the REST web serivce. Can anyone advise how to update this programatically? I have identified all the other elements in the web service

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the e URL is

{{base_url}}/fscmRestApi/resources/11.13.18.05/itemTemplates/

The documentation from Oracle is at

REST API for Oracle Supply Chain Management Cloud - Item Templates REST Endpoints