Splat parameter without name is discarded in documentation signature

[AaronC81]

If * is used as an argument inside a method signature, this argument is not shown in the generated documentation. This is causing this issue in one of my projects.

Steps to reproduce

Generate YARD documentation for this code:

class A
  def x(a, b, *); end
end

Actual Output

Expected Output

The method signature in the documentation should be #x(a, b, *) => Object.

Environment details:

• OS: Ubuntu 18.04
• Ruby version (ruby -v): ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-linux-gnu]
• YARD version (yard -v): yard 0.9.20

I have read the Contributing Guide.