developer/api/v1/addons/Get-AddonInstance.ps1

function Get-AddonInstance
{
    param(
        [Parameter(Mandatory)]
        [string] $AddonAlias,
        [Parameter(Mandatory)]
        [string] $InstanceAlias
    )

    return Invoke-Api Get "/developer/api/v1/addons/$AddonAlias/$InstanceAlias"
}