if (executions.size() == 0) { firstExecTime = lastExecTime; return; }
	public ChainExecutions(Collection executions) {		Iterator iter = executions.iterator();		ChainExecutionData exec;				while (iter.hasNext()) {			exec = (ChainExecutionData) iter.next();			addChainExecution(exec);			Date date = exec.getDate();			long time = date.getTime();			if (time < firstExecTime)				firstExecTime = time;			if (time >lastExecTime)				lastExecTime = time;		}				// build list of chain names		getChainNames();				// build list of dataset names.		getDatasetNames();	}