Enable two-phase rendering for a portlet

By default, two-phase rendering is turned off. To enable two-phase rendering for a portlet, update the portlet.xml deployment descriptors for the portlet.

Edit portlet.xml for the portlet. Add the following entry to the file:

<portlet>
    ...
    <container-runtime-option>
        <name>javax.portlet.renderHeaders</name>
        <value>true</value>
    </container-runtime-option>
</portlet>

Parent: Use two-phase rendering with JSR 286 portlets