public static Builder build() {
        return new Builder();
    }
This is an "empty" implementation only present for compatibility with {@link Io}.  GraphML is a "whole graph"
serialization format and does not have the notion of generic serialization functions.

@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/structure/io/graphml/GraphMLMapper.java