HttpRequest request = mBlobStoreContext.getSigner()
HttpResponse response = mBlobStoreContext.utils().http().invoke(request);
When pointing to s3 custom endpoint and trying to get the response from the GET Request it fails with SignatureDoesNotMatch message in the AWSResponseException. Strange behavior is that it has no issues while PUT requests so it has nothing wrong with the Access Key and the Secret Key.
V4 Signature is used for Authorization.