As pointed in http://stackoverflow.com/questions/39617729/oinputfile-optional-and-accept-validation?noredirect=1#comment66544309_39617729 I'm not able to use an inputFile and leave it blank if the accept field is not empty.
It happens in any browser (chrome and edge)
I'm providing a sample project
Myfaces 2.2.10, tomee
This is caused by MyFaces.
Fix #315: implicitly convert empty parts to null
This will align MyFaces behavior with Mojarra
o:inputFile will now by default always consider empty parts as null.
#315: add integration test for o:inputFile
#315: add empty file case to o:inputFile IT