Missing API interface FileInterface::getNameWithoutExtension
The method getNameWithoutExtension was added to the interface FileInterface in #41768. It was implemented correctly, but due to a syntax error in the closing phpdoc comment header it was never officially part of the interface.
We need to fix this. Undecided yet if we will backport that addition to 6.1 and 6.0, but it seems to make sense.
Most classes will probably subclass AbstractFile which already contains this methods, so there shouldn't be a problem for these. Only affected classes could be extensions implementing the interface directly.