1. First ground of appeal: The principle of energy solidarity is not a legal criterion, and does not impose on executive bodies an obligation to act.
2. Second ground of appeal: The principle of energy solidarity was not applicable in the present case.
3. Third ground of appeal: The European Commission observed the principle of energy solidarity.
4. Fourth ground of appeal: It was not necessary for the principle of energy solidarity to be referred to expressly in the decision contained in the decision.
5. Fifth ground of appeal: Contested Commission Decision C(2016)6950 cannot be annulled simply on account of an alleged procedural error.