Fix Invoice class to not call validateData

[eileenmcnaughton]

Overview

This avoids calling the BaseIPN validateData class from Invoice.php and calls the narrower
loadRelatedObjects to avoid having to change the code around it

Before

Hacky use of BaseIPN

After

Somewhat less hacky call to loadRelatedObjects

Technical Details

Per

civicrm-core/CRM/Contribute/Form/Task/Invoice.php

Line 363 in 1bd50d0

'display_name' => $contribution->_relatedObjects['contact']->display_name,

display_name is accessed from relatedObjects so I added that check to the test

Comments

[civibot]

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[KarinG]

I was going to look at this now but I see it's already been merged :-)

[eileenmcnaughton]

@KarinG please still test - I don't think @mattwire tested it