You need to iterate on value:

 // extract json content from the request:
 set dynRequestJsonPayload = {}.%FromJSON(%request.Content)
 #dim JsonIterator As %Iterator.AbstractIterator
 set JsonIterator = dynRequestJsonPayload.%GetIterator()
 
 // iterate on json structure:
 if dynRequestJsonPayload '= "" {
    while JsonIterator.%GetNext(.key, .value, .NodeType) { 
      if NodeType = "string" {
        do GlobalTrace("NodeType: " _ NodeType _ "; key: " _ key _ "; value: " _ value)
      } elseif NodeType = "array" {
         // i want to iterate on this array...
         // the following line throws the exeception "ERREUR #5002: Erreur ObjectScript: <INVALID OREF>traitementUFI+34^common.REST.1"
         set JsonIteratorSecondary = value.%GetIterator()
      } else {
	      // Do something
      }

    }
}

You can set it programmatically:

set package = ##class(%PackageDefinition).%OpenId("User",,.sc)
 
zw package
package=2@%Library.PackageDefinition  ; <OREF>
+----------------- general information ---------------
|      oref value: 2
|      class name: %Library.PackageDefinition
|           %%OID: $lb("User","%Library.PackageDefinition")
| reference count: 2
+----------------- attribute values ------------------
|       %Concurrency = 1  <Set>
|         ClientName = ""
|        Description = ""
|       GlobalPrefix = ""
|               Name = "User"
|          OwnerName = ""
|          RtnPrefix = ""
|            SQLName = ""
+----------------- swizzled references ---------------
|             i%list = ""  <Set>
|             r%list = ""  <Set>
+-----------------------------------------------------

What's "RO" stand for?  

ReadOnly.

After the customer deployment, if there is any change made on the production settings (e.g. changing an AE Title on the DICOM service), those settings are stored in the APPCODE, and the settings will be lost after a container PODS restart (kubernetes recreating the PODS).

Two ways to avoid that: