Add attribute to user in SCIM 2.0 Test App (OAuth Bearer Token) without external namespace in provisioning

Hi, everyone,

I'm trying to add additional attribute(e.g. mobilePhone) to user in SCIM 2.0 Test App (OAuth Bearer Token) using external namespace as urn:ietf:params:scim:schemas:core:2.0:User, so that when I start provision from Okta, I expect it to be in phoneNumbers array near primary(work) phone. But instead, I receive user object with phoneNumber object inside "urn:ietf:params:scim:schemas:core:2.0:user" property

Example:

{..."phoneNumbers":[{"type":"work","primary":true,"value":"SomePrimaryNumber"}],

"urn:ietf:params:scim:schemas:core:2.0:user":{"phoneNumbers":[{"type":"mobile","value":"someNumberhere"}]},",

"userName": ...}

Any suggestions, how to make Okta send users as

{..."phoneNumbers":[{"type":"work","primary":true,"value":"SomeP