@reta ,
Thanks for the response,
Yes you are right, I mean signing with AWS Sig v4.
I investigated using AwsSdk2Transport as well, As I asked here, I have 2 issues using it which has not been addressed yet.
The good thing about using ApacheHttpClient5Transport was that I had option to choose between http and https for running local integration tests by http.
I tried to use GitHub - acm19/aws-request-signing-apache-interceptor,
It is working fine for GET requests but ES returning 403 for PUT requests and it looks like signing is not happening properly.