I commented out mixins and it does not work. Got exception:
javax.jcr.nodetype.ConstraintViolationException: No valid property definition on node '/cmis/My_Folder-0-0/My_Document-1-0' with primary type 'ComplexType' and mixin types [] for the property: jcr:uuid="114"
I assume this means import of types did not perform properly and there is no info that ComplexType is sub-type of nt:file.