Can't get parameters for Java class constructor in .class

Background: I have a .jar library loaded (with sources) that includes a Java class with a constructor.

I am trying to get the parameters for that constructor. I am able to get a ClsMethodImpl for it, but the .containingFile is the .class. When I ask for the parameters, I get an empty array. Also, if I try to get the .navigationElement to go to the .java file, I just get the same ClsMethodImpl instance. If I get the .parent, ClsClassImpl though, its .navigationElement is the PsiClassImpl in the .java.

I need to get the parameters of the constructor in order to determine whether one of them is annotated, but I don't seem to be able to retrieve them.