public long getMinMetaId() {
        return minMetaId;
    }
This shows the window that the tasks are being created from. When a
tracker starts this is the first item that it creates. When a tracker has
done everything available at a given time (i.e. lastPollTaskCount = 0)
this resets to the poll count. For example you may process all streams
since a year ago and so half way through you would get a tracker 50% and
once it completes it would read 100%. If then some more data came in it
would show the % complete since the last complete time.
stroom-core-shared/src/main/java/stroom/processor/shared/ProcessorFilterTracker.java