Gem::SpecificationPolicy#validate_non_files

# File tmp/rubies/ruby-4.0.0/lib/rubygems/specification_policy.rb, line 284
def validate_non_files
  return unless packaging

  non_files = @specification.files.reject {|x| File.file?(x) || File.symlink?(x) }

  unless non_files.empty?
    error "[\"#{non_files.join "\", \""}\"] are not files"
  end
end