...
- In the parameters section:
<parameter name="defaultContentType" locked="false">empty/content<>"empty/content"</parameter> - In the message builders section:
<messageBuilder contentType="empty/content" class="org.wso2.carbon.relay.BinaryRelayBuilder"/> - In the message formatters section:
<messageFormatter contentType="empty/content" class="org.wso2.carbon.relay.ExpandingMessageFormatter"/>
...