public void writeStartDocument(String encoding, String version)
                throws XMLStreamException {
            super.writeStartDocument(encoding, version);
            super.writeCharacters("\n");
        }
Print indentation for the current level.

@exception org.xml.sax.SAXException
             If there is an error writing the indentation characters, or if
             a filter further down the chain raises an exception.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/structure/io/graphml/GraphMLWriterHelper.java