if (identifier == null)
throw ParseUtils.missingRequired(reader, Collections.singleton(Attribute.IDENTIFIER));
if (identifiers.contains(identifier))
throw new XMLStreamException(element.getLocalName() + " already declared", reader.getLocation());
subsystemState.addModule(new OSGiModule(identifier, start));
identifiers.add(identifier);
ParseUtils.requireNoContent(reader);
} else {
throw ParseUtils.unexpectedElement(reader);