switch(attributeName)
{
    case {attributeName} :
        log.info("Currently switching on value... ${attributeName}")

    case user.getFirstNameMapping():
        model.user.userInfo.firstName = attributeValue
        break
    case user.getLastNameMapping():
        model.user.userInfo.lastName = attributeValue
        break
    case user.getAuthenticationKeyMapping():
        model.authenticationValue = attributeValue
        break
    case user.getEmailMapping():
        model.email = attributeValue.toLowerCase()
        break
}

if(attributeName.equals(user.getFirstNameMapping())
{
    ...
}

switch(true)
{
    case {attributeName} :
        log.info("Currently switching on value... ${attributeName}")
    case {user.getFirstNameMapping().equals(attributeName)}:
        model.user.userInfo.firstName = attributeValue
        break
    case {user.getLastNameMapping().equals(attributeName)}:
        model.user.userInfo.lastName = attributeValue
        break
    case {user.getAuthenticationKeyMapping().equals(attributeName)}:
        model.authenticationValue = attributeValue
        break
    case {user.getEmailMapping().equals(attributeName)}:
        model.email = attributeValue.toLowerCase()
        break
}