From: Sergey Beryozkin <sberyozkin_at_talend.com>
Date: Thu, 9 May 2013 12:59:40 +0100

Hi All,

I can see there are some expectations MultivaluedMap are supposed to
support null keys. I don't see anything in JavaDocs about it and IMHO we
should not allow JAX-RS developers to do

map.putSingle(null, something);

Thanks, Sergey