Lower case API Gateway Query Params

aws-api-gw-mapping.vtl

#set($queryMap = $input.params().querystring)
$input.json("$")
#foreach( $key in $queryMap.keySet())
  #if($queryMap.get($key))
    #if($key.toLowerCase() == "id")
        #set($context.requestOverride.querystring.id = "$util.urlDecode($queryMap.get($key))")
    #end
    #if($key.toLowerCase() == "params")
        #set($context.requestOverride.querystring.params = "$util.urlDecode($queryMap.get($key))")
    #end
    #if($key.toLowerCase() == "country")
        #set($context.requestOverride.querystring.country = "$util.urlDecode($queryMap.get($key))")
    #end
    #if($key.toLowerCase() == "languagecode")
        #set($context.requestOverride.querystring.languageCode = "$util.urlDecode($queryMap.get($key))")
        #end
  #end
#end

Great example how to handle these parameters!