panel1.xml

<row>
    <chart>
        <title>Messages per adapter last 2 hours</title>
        <searchString>index="audit-trail" | timechart span="5m" limit=25 count(adapterName) by adapterName</searchString>
        <earliestTime>rt-2h</earliestTime>
        <latestTime>rt</latestTime>  <option name="charting.chart">area</option>
        <option name="charting.chart.nullValueMode">gaps</option>
        <option name="charting.chart.stackMode">stacked</option>
        <option name="charting.layout.splitSeries">false</option>
        <option name="charting.legend.labelStyle.overflowMode">ellipsisMiddle</option>
        <option name="charting.legend.placement">right</option>
        <option name="height">450px</option>
    </chart>
</row>