protected <T extends TinkerElement> void markRead(TinkerElementContainer container) {
        if (!isOpen()) txNumber.set(openedTx.getAndIncrement());

        if (null == txReadElements.get())
            txReadElements.set(new HashSet<>());

        txReadElements.get().add(container);
    }
Adds element to list of read in current transaction.
tinkergraph-gremlin/src/main/java/org/apache/tinkerpop/gremlin/tinkergraph/structure/TinkerTransaction.java