List, Set, and OrderedSet in form should be handled as per jax-rs standard Look at page 12 In section 3.2 of the spec. See issue #195. This makes it work with CXF given that you have provided a jackson ParamConverter to CXF
Merge pull request #197 from BiovistaInc/jaxrs-compliant-lists-as-formparameters

Handling QueryListTypes in Forms (resubmit)