code: private StateVertex putIfAbsent(StateVertex stateVertex, boolean correctName) {
  		writeLock.lock();
  		try {
  			boolean clone = this.hasClone(stateVertex);
  			if (!clone) {
  				setNearDuplicate(stateVertex);
  
  				boolean added = sfg.addVertex(stateVertex);
  				if (!added)
  					LOG.info("Vertex should be added !!" + stateVertex);
  				stateById.put(stateVertex.getId(), stateVertex);
  				int count = stateCounter.incrementAndGet();
  				exitNotifier.incrementNumberOfStates();
  				LOG.info("Number of states in the graph is now {}", count);
  				return null;
  			} else {
  				// Graph already contained the vertex
  				LOG.debug("Graph already contains vertex {}", stateVertex);
  				return this.getStateInGraph(stateVertex);
  			}
  		} finally {
  			writeLock.unlock();
  		}
  	}
docs: detection <near duplicates?>