public static QualifierFilter restoreFilterXml(XmlPullParser parser) throws XmlParseException {
		QualifierFilter filter;
		XmlElement elemId = parser.peek();
		String nm = elemId.getName();
		if (nm.equals(ELEM_VARARGS.name())) {
			filter = new VarargsFilter();
		}
		else if (nm.equals(ELEM_POSITION.name())) {
			filter = new PositionMatchFilter(-1);
		}
		else if (nm.equals(ELEM_DATATYPE_AT.name())) {
			filter = new DatatypeMatchFilter();
		}
		else {
			return null;
		}
		filter.restoreXml(parser);
		return filter;
	}
Instantiate a qualifier from the stream. If the next element is not a qualifier,
return null.
@param parser is the given stream decoder
@return the new qualifier instance or null
@throws XmlParseException for problems decoding the stream
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/lang/protorules/QualifierFilter.java