FOP if before fox:external-document

Question

I have a FOP like this:

<fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format" xmlns:fox="http://xmlgraphics.apache.org/fop/extensions">
    <fo:layout-master-set>
        <fo:simple-page-master master-name="A4" page-width="210mm" page-height="297mm" margin-top="10mm"
                               margin-bottom="10mm" margin-left="10mm" margin-right="10mm">
            <fo:region-body margin="10mm"></fo:region-body>
        </fo:simple-page-master>
    </fo:layout-master-set>

    <fo:page-sequence master-reference="A4">
        <fo:flow flow-name="xsl-region-body">
            <!-- Contenuto del flusso -->
            <fo:block>
                <#if body.payload.data.destination = 'Europe'>
                    <fox:external-document content-type="pdf" src="url('${body.payload.data.pdf}')"/>
                </#if>
            </fo:block>
        </fo:flow>
    </fo:page-sequence>
</fo:root>

but I'm not able to insert the if before to <fox:external-document

Is there a solution?

I'm using:

<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-freemarker</artifactId>
  <version>3.21.0</version>
</dependency>
<dependency>
   <groupId>org.apache.camel</groupId>
   <artifactId>camel-fop</artifactId>
   <version>3.21.0</version>
</dependency>