internal/functions/ConvertTo-AuthHeader.ps1

function ConvertTo-AuthHeader {
<#
    .SYNOPSIS
        Generates an authentication header from a graph token.
     
    .DESCRIPTION
        Generates an authentication header from a graph token.
     
    .PARAMETER Token
        The token from which to build the authentication header.
     
    .EXAMPLE
        PS C:\> Get-Token | ConvertTo-AuthHeader
     
        Generates an authentication header from a graph token.
#>

    [CmdletBinding()]
    param (
        [Parameter(ValueFromPipeline = $true)]
        $Token
    )
    
    process {
        foreach ($tokenObject in $Token) {
            @{
                Authorization = "Bearer $($tokenObject.AccessToken)"
                'Content-Type' = 'application/json'
                'Accept'      = 'application/json, text/plain'
            }
        }
    }
}