docs: private static Map<String, String> initializeAwsIdentityDocument() {
      InputStream stream = null;
      try {
        stream = openStream(AWS_INSTANCE_IDENTITY_DOCUMENT_URI);
        String awsIdentityDocument = slurp(new InputStreamReader(stream, Charset.forName("UTF-8")));
        return parseAwsIdentityDocument(awsIdentityDocument);
      } catch (IOException e) {
        // Cannot connect to http://169.254.169.254/latest/dynamic/instance-identity/document.
        // Not on an AWS EC2 instance.
      } finally {
        if (stream != null) {
          try {
            stream.close();
          } catch (IOException e) {
            // Do nothing.
          }
        }
      }
      return Collections.emptyMap();
    }