[ixpmanager] Upgrade to v6 -> ContactGroup changes

[Marinos Dimolianis]

Hi all,

We (in GRIX) have developed in the previous version of IXPM (v5.8) a 
functionality that gets from each customer their contacts and from each 
contact the related group values (considering that we pass a customer to 
a function):

$contacts = $customer->getContacts()->getValues();

$contact->getGroups()->getValues()

With the major changes made in the IXPM v6 this does not work as there 
are some organizational changes in the code.

Could you offer some hints on how we can "translate" the existing code 
to the one that will be compatible with the newer IXPM version.

P.S.

I have struggled a lot with identifying the changes and how we can 
translate them but I could not find any appropriate solution.

Thank you in advance,

Marinos