How to get Descriptive FlexField values like columns of parent's API contents via REST API

Hi, experts. I need your help.

As the title, I want to get Descriptive FlexField values as columns via REST API.

I read following manuals for REST APIs.

REST API for Oracle Fusion Cloud SCM - Get all subinventories

REST API for Oracle Fusion Cloud SCM - Get all flexfields

Then I could got DFF values by 2 steps.

However, I need to execute REST APIs for each subinventory to get DFF values.

This is not realistic.

Please teach me how to get DFF values via REST API only 1 step.(/fscmRestApi/resources/11.13.18.05/subinventories/)

1st Step.

/fscmRestApi/resources/11.13.18.05/subinventories/

⇒

{

  "items" : [ {

    "AssetSubinventory" : 1,

    "DefaultCountTypeCode" : "4",