I've the following XML
<lsfIndicatorEvent>
   <startDate>2016-08-08T13:40:00.000+01:00</startDate>
</lsfIndicatorEvent>
and inside the filter, have the multiline plugin and the xml as followed:
xml {
    source => "message"
    target ="xml_message"
    store_xml => false
    xpath => [
	"/lsfIndicatorEvent//dimension[1]/text()" , "layer",
        "/lsfIndicatorEvent//startdate/text()", "startDate"
        ]
}
I can get the layer and the startDate as strings, but now I can't convert that startDate to date without giving me, failed parsing date.