private void reset() {
        mapName = null;
        key = null;
        rangeFrom = null;
        rangeTo = null;
        haveSeenXmlInValueElement = false;
        valueXmlDefaultNamespaceUri = null;
        time = null;
        timeout = null;
        currentTags = null;
    }
This method applies a post processing function if we are currently within
a function element. At this stage we should have details of the function
to apply from the corresponding start element and content to apply it to
from the characters event.

@param uri       The element's Namespace URI, or the empty string.
@param localName The element's local key, or the empty string.
@param qName     The element's qualified (prefixed) key, or the empty string.
@throws SAXException The client may throw an exception during processing.
@see AbstractXMLFilter#endElement(String,
String, String)
stroom-state/stroom-planb-impl/src/main/java/stroom/planb/impl/pipeline/PlanBFilter.java