public T vertexProcessor(final BiConsumer<Vertex, Map<String, Object>> vertexProcessor) {
            this.vertexProcessor = Optional.ofNullable(vertexProcessor);
            return extendingClass.cast(this);
        }
The function supplied here may be called more than once per vertex depending on the implementation.
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/algorithm/generator/AbstractGenerator.java