Bulk update custom user profile properties for SharePoint Online

And here is the script:

# Get needed information from the end user
$adminUrl = Read-Host -Prompt 'Enter the admin URL of your tenant'
$userName = Read-Host -Prompt 'Enter your user name'
$pwd = Read-Host -Prompt 'Enter your password' -AsSecureString
$importFileUrl = Read-Host -Prompt 'Enter the URL to the file located in your tenant'

# Get instances to the Office 365 tenant using CSOM
$uri = New-Object System.Uri -ArgumentList $adminUrl
$context = New-Object Microsoft.SharePoint.Client.ClientContext($uri)

$context.Credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($userName, $pwd)
$o365 = New-Object Microsoft.Online.SharePoint.TenantManagement.Office365Tenant($context)
$context.Load($o365)

# Type of user identifier ["Email", "CloudId", "PrincipalName"] in the user profile service
$userIdType=[Microsoft.Online.SharePoint.TenantManagement.ImportProfilePropertiesUserIdType]::PrincipalName

# Name of user identifier property in the JSON
$userLookupKey="UserName"

# Create property mapping between the source file property name and the Office 365 property name
# Notice that we have here 2 custom properties in UPA called 'City' and 'OfficeCode'
$propertyMap = New-Object -type 'System.Collections.Generic.Dictionary[String,String]'
$propertyMap.Add("CellPhone", "CellPhone")


# Call to queue UPA property import
$workItemId = $o365.QueueImportProfileProperties($userIdType, $userLookupKey, $propertyMap, $importFileUrl);

# Execute the CSOM command for queuing the import job
$context.ExecuteQuery();

# Output the unique identifier of the job
Write-Host "Import job created with the following identifier:" $workItemId.Value