Camel undertow component forces to set "text/plain" even Rest DSL sets "application/json" to "produces" option

Issue

Even Rest DSL sets "application/json" to "produces" option, camel-undertow overrides the content-type header values with "text/plain" when the exchange body is null.

    <camelContext id="camel" xmlns="http://camel.apache.org/schema/spring">
        <restConfiguration bindingMode="auto" component="undertow"
            contextPath="test" host="localhost" port="8005"/>
        <rest id="rest-0b0215bd-f133-46f8-968c-4fe21ba4af4f" path="demo">
            <get id="get-1" produces="application/json" uri="/ping">
                <description>direct:hello</description>
                <route>
                    <to uri="direct:hello"/>
                </route>
            </get>
        </rest>
        <route id="simple-route">
            <from id="_from1" uri="direct:hello"/>
            <setBody id="_setBody1">
                <simple>${null}</simple>
            </setBody>
            <log id="route-log" message=">>> ${body}"/>
        </route>
    </camelContext>