@Override
    public Set<VertexComputeKey> getVertexComputeKeys() {
        return VERTEX_COMPUTE_KEYS;
    }
@author Daniel Kuppitz (http://gremlin.guru)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/search/path/ShortestPathVertexProgram.java