class Aws::S3::EncryptionV2::DecryptHandler

def envelope_from_metadata(context)
  possible_envelope = {}
  POSSIBLE_ENVELOPE_KEYS.each do |suffix|
    if value = context.http_response.headers["x-amz-meta-#{suffix}"]
      possible_envelope[suffix] = value
    end
  end
  extract_envelope(possible_envelope)
end