gen/writers/metadata.go
func (c *MetadataWriter) WriteHeader(pkg string, w io.Writer) error {
	return c.headerTmpl.Execute(w, pkg)
}
func (c *MetadataWriter) WriteHeader(pkg string, w io.Writer) error {
	return c.headerTmpl.Execute(w, pkg)
}
// WriteHeader writes the generic header text.