If the resource target isn't found then an incomplete jnlp file is generated without any warning to the user. Ideally this would at a minimum print a warning and perhaps fail the build.

<fx:deploy width="1020" height="700"
                  outdir="${basedir}/${dist.dir}" embedJNLP="true"
                  outfile="${application.title}">
            <fx:application refId="sampleApp"/>
            <fx:resources>
                <fx:fileset dir="${basedir}/${dist.dir}"
                            includes="SOME_FILE_THAT_DOESN"T_EXIST.jar"/>
            </fx:resources>
            <info title="Sample app: ${application.title}"
                  vendor="${application.vendor}"/>
        </fx:deploy>