from("jms:so")
            .setHeader("comment").xpath("//comment()", String.class)
            .setHeader("firstComment").xpath("//comment()[1]", String.class)
            .log("comment is ${headers.comment}")
            .log("first comment is ${headers.firstComment}")
            .to("jms:so.out");

<StackOverflow>
    <!--Camel-->
    <Nested>
    <!--Nested Camel-->
    </Nested>
</StackOverflow>