Up to zanata-client 3.6.0, the "file types" option was a comma-separated list of file extensions. In https://bugzilla.redhat.com/show_bug.cgi?id=1186972 (v 3.7), this was changed to be a list of file types with the corresponding extensions (semicolon-separated) in square brackets - any user passing in a comma-separated list of extensions as before would get different behaviour from before - probably "Invalid expression for '--file-types' option".
(In the code, there is an attempt at a helpful error message when extensions are provided, but as far as I can tell, it will only work if the extensions are in square brackets, separated by semicolons.)
In the case of the Maven client, the default value for the fileTypes parameter is still specified as a comma-separated list of extensions, even though the code in RawPushCommand can't handle this any more. See ZNTA-993.
Given that "File" support is experimental, perhaps a breaking change could be justified, but it should at least have been documented in the client release notes, and the Maven client updated at the same time.