private/core/Get-ZtTenantName.ps1

function Get-ZtTenantName {
    <#
    .SYNOPSIS
        Try and resolve the displayname of the specified tenant.

    .DESCRIPTION
        Try and resolve the displayname of the specified tenant.
        Will return the ID if doing so fails.

    .PARAMETER TenantId
        The ID of the tenant to get the name for

    .EXAMPLE
        PS C:\> Get-ZtTenantName -TenantId $myTenant

        Retrieves the displayname of the tenant in $myTenant
    #>

    [CmdletBinding()]
    param(
        $TenantId
    )

    $tenant = Get-ZtTenant -TenantId $TenantId
    if ($tenant -and $tenant.displayName) {
        return $tenant.displayName
    }
    # Fall back to the ID
    $TenantId
}