ConvertFrom-Json flattens single-item arrays into objects when opening brace of JSON isn't on first line #18804

Prerequisites

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Steps to reproduce

When using ConvertFrom-Json to convert a JSON file to a PSCUstomObject, I have run into a weird behavior when the JSON's main object doesn't start on line 1, but instead starts either with a blank line, or a comment (In this case I put a comment there to prevent any trim function to strip the newline, but the result is the same whether or not the first line is a comment or just blank, as long as it isn't {

Take the following JSON file, test.json in the behavior examples below:

// This file contains test data
{
  "testArray": [
    {
      "name": "test"
    }
  ],
  "testArray2": [
    {
      "name": "test2"
    },
    {
      "name": "test3"
    }
  ]
}

And process it with ConvertFrom-Json, you'd expect it to be the same as when processing the following file:

{
  "testArray": [
    {
      "name": "test"
    }
  ],
  "testArray2": [
    {
      "name": "test2"
    },
    {
      "name": "test3"
    }
  ]
}

But in the first case, testArray is represented as a PSCUstomObject, not an array of objects.

Expected behavior

PS> $testContent = Get-Content test.json | ConvertFrom-Json

PS> $testContent.testArray.GetType()

IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     True     Object[]                                 System.Array

Actual behavior

PS> $testContent = Get-Content test.json | ConvertFrom-Json

PS> $testContent.testArray.GetType()

IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     False    PSCustomObject                           System.Object

Error details

No response

Environment data

PS> $PSVersionTable

Name                           Value
----                           -----
PSVersion                      7.3.1
PSEdition                      Core
GitCommitId                    7.3.1
OS                             Microsoft Windows 10.0.22623
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Visuals

No response