Eclipse 4.3 product 'export'

With Eclipse 4.2, 'export' not possible at all, fails with
java.lang.NoClassDefFoundError:
at/bestsolution/efxclipse/tooling/pde/adaptor/IClasspathContributor
, see also
https://groups.google.com/forum/?fromgroups=#!topic/efxclipse/ZoYFeIT7oes