The legal basis for claiming priority in the EP is Article 87. Paragraph 1 reads
"Any person who has duly filed, in or for
(a) any State party to the Paris Convention for the Protection of Industrial Property or
(b) any Member of the World Trade Organization,
an application for a patent, a utility model or a utility certificate, or his successor in title, shall enjoy, for the purpose of filing a European patent application in respect of the same invention, a right of priority during a period of twelve months from the date of filing of the first application."
So there are the following conditions to be met:
1) country or State that falls within the above definition (member of PC or WTO); 2) same person OR successor in title; 3) 12 month period; 4) first patent application (or utility model etc); 5) the same invention.
The most trivial conditions are the same person OR successor in title and the first patent application aka "first filing". So a US provisional IS a first filing, while an continuation-in-part is not. Also, a US normal filing, stemming from a US provisional is not a first filing and cannot be used to claim priority.
In your example provisional PP1 (01.12.2016) can be used to claim priority whithin the 12 month window (and 30.11.2016 is there), but the US appl. filed on 30.12.2016 cannot. Mind that, the response to a deficient priority claim might not be instant, the EPO performs an initial formalities check (file No, dates, copies) and beyond that it's the examining division's responsibility to declate a priority claim invalid. So if someone has claimed an US continuation-in-part for claiming priority, he will deal with this in the substantive examination phase.