Migrate version is actually 9.5.11 but the popup selector does not have that version listed.
I am calling a method which returns an object that implements a MigrateDestinationInterface object (the return type of the method is MigrateDestinationInterface), and then I call getDerivativeId() on that object. The code works fine.
However, when analyzed with phpstan, I get the following error message:
Call to an undefined method Drupal\migrate\Plugin\MigrateDestinationInterface::getDerivativeId().
This is because this method is not declared in MigrateDestinationInterface. If I declare it there, the issue goes away.
I have used getDerivativeId() on many MigrateDestination objects, and have never yet encountered one that did not implement getDerivativeId(). Code samples I have seen online also seem to assume that this method should always exist on a MigrateDestination. So, would I be wrong to think that perhaps this method should be declared in the Interface?
Closed: works as designed
2.0
Code
Of course, shortly after posting, I did find a destination plugin that does not derive from Entity and therefore doesn't implement getDerivativeId(). So this question is moot :(