WebHDFS HA enablement in web.xml is sensitive to order of context listeners

Depending on how the web.xml gets generated, the HaServletContextListener may come after the UrlRewriteServletContextListener, in which case the provider is not available to the rewrite framework on initialization and HA functionality does not work.

The web.xml config that works is:

<listener>
<listener-class>org.apache.hadoop.gateway.services.GatewayServicesContextListener</listener-class>
</listener>
<listener>
<listener-class>org.apache.hadoop.gateway.ha.provider.HaServletContextListener</listener-class>
</listener>
<context-param>
<param-name>haDescriptorLocation</param-name>
<param-value>/WEB-INF/ha.xml</param-value>
</context-param>
<listener>
<listener-class>org.apache.hadoop.gateway.filter.rewrite.api.UrlRewriteServletContextListener</listener-class>
</listener>
<context-param>
<param-name>rewriteDescriptorLocation</param-name>
<param-value>/WEB-INF/rewrite.xml</param-value>
</context-param>

but there is no guarantee in place that the web.xml will be generated as such.