@Override
    public Set<VertexComputeKey> getVertexComputeKeys() {
        return new HashSet<>(Arrays.asList(
                VertexComputeKey.of(property, false),
                VertexComputeKey.of(TraversalVertexProgram.HALTED_TRAVERSERS, false)));
    }
Identifies "Connected Component" instances in a graph by assigning a component identifier (the lexicographically
least string value of the vertex in the component) to each vertex.

@author Stephen Mallette (http://stephen.genoprime.com)
@author Daniel Kuppitz (http://gremlin.guru)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/clustering/connected/ConnectedComponentVertexProgram.java