SyncMadeEasy/force-app/main/default/classes/UpdateInventoryLevelsAuthentication.cls

@RestResource(urlMapping='/UpdateInventoryLevelsAuthentication/*')
global with sharing class UpdateInventoryLevelsAuthentication {
    
    @HttpPost
    global static void updateInventoryLevelsWithAuthentication(){       
       //Deprecated
       //Class no longer exists  
    }      
}