Add Object to HashTable

gistfile1.txt

# Courtesy of /u/LordZillion from /r/PowerShell
$Users = Import-Csv -Path C:\Temp\AllTheUsers.csv
$HashTable = @{}

Foreach($User in $Users) {
    [int]$HashTableReference = $User.ExternalID
    $HashTable[$HashTableReference] += New-Object -TypeName PSObject -Property @{
        'UserName'  = ($User.UserName);
        'Password'  = ($User.Password);
        'Email'     = ($User.Email);
        'FirstName' = ($User.FirstName);
        'LastName'  = ($User.LastName);
        'FullName'  = ($User.FirstName +' '+ $User.LastName)
    }
}