Parameter `secureString` transforms input incorrectly on adapter

Prerequisites

• Write a descriptive title.
• Make sure you are able to repro it on the latest version
• Search the existing issues.

Summary

Whilst working on #1208, another issue popped up. I have the following configuration document:

$schema: https://aka.ms/dsc/schemas/v3/bundled/config/document.json
parameters:
  myString:
    type: secureString
    defaultValue: "MySecret"
resources:
- name: Class-resource Info
  type: TestClassResource/TestClassResource
  properties:
    Name: 'TestClassResource'
    SecureStringProp: "[parameters('myString')]"

Instead of parsing the input through the adapter as such (seen in the logging):

{"resources":[{"name":"TestClassResource/TestClassResource","type":"TestClassResource/TestClassResource","properties":{"Name":"TestClassResource","SecureStringProp":"MySecret"}}],"metadata":{"Microsoft.DSC":{"context":"configuration"}}}

It does it like:

jsonInput={"resources":[{"name":"TestClassResource/TestClassResource","type":"TestClassResource/TestClassResource","properties":{"Name":"TestClassResource","SecureStringProp":{"secureString":"MySecret"}}}],"metadata":{"Microsoft.DSC":{"context":"configuration"}}}

Which results in the following error: Exception setting "SecureStringProp": "Cannot create object of type "System.Security.SecureString". The property 'secureString' was not found for the 'System.Security.SecureString' object. There is no settable property available."

Steps to reproduce

See steps above.

Expected behavior

The secure string is parsed as string

Actual behavior

The secure string is parsed as object

Error details

Environment data

Name                           Value
----                           -----
PSVersion                      7.5.3
PSEdition                      Core
GitCommitId                    7.5.3
OS                             Microsoft Windows 10.0.26100
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Version

dsc 3.2.0-preview.6

Visuals

No response

Start by reproducing the issue with the YAML configuration document and inspect the adapter logging to trace where the secureString value becomes an object. Confirm the adapter emits SecureStringProp as "MySecret" rather than {"secureString":"MySecret"}, and verify the configuration applies successfully to the TestClassResource resource.