public static Class<? extends OutputFormat> getOutputFormat(final Class<? extends InputFormat<NullWritable, VertexWritable>> inputFormat) {
        return INPUT_TO_OUTPUT_CACHE.get(inputFormat);
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
hadoop-gremlin/src/main/java/org/apache/tinkerpop/gremlin/hadoop/structure/io/InputOutputHelper.java