class Aws::Rest::Request::Headers

def apply(http_req, params)
  @rules.shape.members.each do |name, ref|
    value = params[name]
    next if value.nil?
    case ref.location
    when 'header' then apply_header_value(http_req.headers, ref, value)
    when 'headers' then apply_header_map(http_req.headers, ref, value)
    end
  end
end