Time passed in punctuate call is currentTime, not punctuate schedule time.

The java doc specifies that for a Transformer, calling context.schedule calls punctuate every 1000ms. This is not entirely accurate, as if no data is received for a while, punctuate won't be called.

     *             void init(ProcessorContext context) {
     *                 this.context = context;
     *                 this.state = context.getStateStore("myTransformState");
     *                 context.schedule(1000); // call #punctuate() each 1000ms
     *             }

When you receive new data say after 20 seconds, punctuate will play catch up and will be called 20 times at reception of the new data.

the signature of punctuate is

*             KeyValue punctuate(long timestamp) {
     *                 // can access this.state
     *                 // can emit as many new KeyValue pairs as required via this.context#forward()
     *                 return null; // don't return result -- can also be "new KeyValue()"
     *             }

but the timestamp being passed is currentTimestamp at the time of the call to punctuate, not at the time the punctuate was scheduled. It is very confusing and I think the timestamp should represent the one at which the punctuate should have been scheduled. Getting the current timestamp is not adding much information as it can easily obtained using System.currentTimeMillis();