get thumbprint of a service principal

$tenantId ="<tenant id>"
#use the goabl admin account to login 
Connect-AzureRmAccount -Tenant $tenantId

$certificateObject = New-Object System.Security.Cryptography.X509Certificates.X509Certificate2
$certificateObject.Import("E:\Cert\examplecert.pfx","Password0123!", [System.Security.Cryptography.X509Certificates.X509KeyStorageFlags]::DefaultKeySet)
Write-Host "the thumbrint of cert"
$certificateObject.Thumbprint

$keyValue = [System.Convert]::ToBase64String($certificateObject.GetRawCertData())

$sp =New-AzureRmADServicePrincipal -DisplayName "jimtestsample" -CertValue $keyValue -EndDate $endDate
$context=Get-AzureRmContext
$token=$context.TokenCache.ReadItems() |Where-Object { ($_.TenantId -eq $tenantId) -and ($_.Resource -eq "https://graph.windows.net/")  }
$accesstoken=$token.AccessToken

$url = "https://graph.windows.net/$tenantId/servicePrincipals/"+$sp.Id+"/keyCredentials?api-version=1.6"

$keyCreds = Invoke-RestMethod -Uri $url  -Method Get -Headers @{"Authorization" = "Bearer $accesstoken"}
Write-Host "--------------------------------------------"
$keyCreds.value | Select-Object customKeyIdentifier