public default Set<MapReduce> getMapReducers() {
        return Collections.emptySet();
    }
The set of {@link MapReduce} jobs that are associated with the {@link VertexProgram}.
This is not necessarily the exhaustive list over the life of the {@link GraphComputer}.
If MapReduce jobs are declared by GraphComputer.mapReduce(), they are not contained in this set.
The default is an empty set.

@return the set of {@link MapReduce} jobs associated with this {@link VertexProgram}
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/VertexProgram.java