为什么go / doc不提供方法？

I'm trying to extract the documentation for various functions an methods using the go/doc package. The code looks pretty much as below. The issue is that it prints/provides only the functions from the package(exported and unexported) but no method regardless if they're exported or unexported. I also tried AllMethods mode with no success. Is this a bug or I'm missing something?

pkg := doc.New(mainPkg, "./", doc.AllDecls)

for _, vv := range pkg.Funcs {
    log.Infof("vv.Name %v, vv.Recv %v", vv.Name,  vv.Recv,  )

}

Iterate through pkg.Types and on each item you can get its Methods.

type Type struct {
  Doc  string
  Name string
  Decl *ast.GenDecl

  // associated declarations
  Consts  []*Value // sorted list of constants of (mostly) this type
  Vars    []*Value // sorted list of variables of (mostly) this type
  Funcs   []*Func  // sorted list of functions returning this type
  Methods []*Func  // sorted list of methods (including embedded ones) of this type
}