public Builder maxDistance(final Number distance) {
            if (null != distance)
                this.configuration.setProperty(MAX_DISTANCE, distance);
            else
                this.configuration.clearProperty(MAX_DISTANCE);
            return this;
        }
Move any valid path into the VP's memory.
@param vertex The current vertex.
@param memory The VertexProgram's memory.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/search/path/ShortestPathVertexProgram.java