It's only my personal opinion, but parameter names with spaces are a really bad idea.
I with Marwim, but it's still probably a bug. Work with My Oracle Support to get that logged.
When executing procedures, in the ANONYMOUS_BLOCK, SQL Developer 4.0.3 incorrectly formats parameters that contain spaces..
The solution is to FIX your code so that it conforms to 'best practices'. That means do NOT use quoted identifiers.
There is not a singlel org I have work with in over 25+ years that would allow a developer to use quoted identifiers.