You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: roa_signature_composer.go
    path of file: ./repos/sealer/vendor/github.com/aliyun/alibaba-cloud-sdk-go/sdk/auth
    
    the code of the file until where you have to start completion: /*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed t
    
func completeROASignParams(request requests.AcsRequest, signer Signer, regionId string) {
	headerParams := request.GetHeaders()

	// complete query params
	queryParams := request.GetQueryParams()
	//if _, ok := queryParams["RegionId"]; !ok {
	//	queryParams["RegionId"] = regionId
	//}
	if extraParam := signer.GetExtraParam(); extraParam != nil {
		for key, value := range extraParam {
			if key == "SecurityToken" {
				headerParams["x-acs-security-token"] = value
				continue
			}
			if key == "BearerToken" {
				headerParams["x-acs-bearer-token"] = value
				continue
			}
			queryParams[key] = value
		}
	}

	// complete header params
	headerParams["Date"] = hookGetDate(utils.GetTimeInFormatRFC2616)
	headerParams["x-acs-signature-method"] = signer.GetName()
	headerParams["x-acs-signature-version"] = signer.GetVersion()
	if request.GetFormParams() != nil && len(request.GetFormParams()) > 0 {
		formString := utils.GetUrlFormedMap(request.GetFormParams())
		request.SetContent([]byte(formString))
		if headerParams["Content-Type"] == "" {
			headerParams["Content-Type"] = requests.Form
		}
	}
	contentMD5 := utils.GetMD5Base64(request.GetContent())
	headerParams["Content-MD5"] = contentMD5
	if _, contains := headerParams["Content-Type"]; !contains {
		headerParams["Content-Type"] = requests.Raw
	}
	switch format := request.GetAcceptFormat(); format {
	case "JSON":
		headerParams["Accept"] = requests.Json
	case "XML":
		headerParams["Accept"] = requests.Xml
	default:
		headerParams["Accept"] = requests.Raw
	}
}