Sample

<topology>
  <gateway>
    ...
    <provider>
      <role>ha</role>
      <name>HAProvider</name>
      <enabled>true</enabled>
      <param>
        <name>webhdfs.ha</name>
        <value>failover_strategy=BaseStrategy;retryCount=3;timeoutInterval=5000</value>
      </param>
    </provider>    
    ...
  <gateway>
  ...
  <service>
    <role>WEBHDFS</role>
    <url>machine1.example.com:50070</url>
    <url>machine2.example.com:50070</url>
  </service>
  ...
</topology>

class X {
}