//map.put("propertySensor1", c1);
//map.put("propertySensor2", c2);
//SensorLookup lookup = new SensorLookupImpl(map);
try {
DateTimeConstant tdc1 = new DateTimeConstant(c1);
DateTimeConstant tdc2 = new DateTimeConstant(c2);
Vector v = new Vector();
v.add(tdc1);
v.add(tdc2);
Expression e = new IsBefore(v,true);