public default void clear(final Configuration configuration) throws Exception {
        clear(null, configuration);
    }
If possible (usually with persisted graph) clear the space on disk given the configuration that would be used
to construct the graph.  The default implementation simply calls
{@link #clear(Graph, Configuration)} with
a null graph argument.
<p/>
Implementations should be able to accept an argument of null for the {@code Configuration} as well, and a
proper handling is needed. Otherwise, a NullPointerException may be thrown.
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/GraphProvider.java