Configure a split-regex transformation

Hello Team,

I've requirement where, I'll hold the value like below on custom sku property(x_availability) of custom product type(TEST).

"724":"IN-STOCK", "746":"OUT-OF-STOCK".

I want to show these values as separated one, in search facets, which I've enabled already. I've gone through the documentation provided by oracle , but which APIs I need to use little confused, could someone able to help on the solution.

I tried below APIs.

1. PUT : /gsadmin/v1/:appName/attributes/:owner
   1. appName is cloud
   2. owner is system.
2. Provided body as below along with all the existing values
   1. "TEST.sku.x_availability": {
      "ecr:type": "property",
      "mergeAction": "update",