TaskSpec rebaseTaskSpecTime(TaskSpec spec) throws Exception {
        ObjectNode node = JsonUtil.JSON_SERDE.valueToTree(spec);
        node.set("startMs", new LongNode(Math.max(time.milliseconds(), spec.startMs())));
        return JsonUtil.JSON_SERDE.treeToValue(node, TaskSpec.class);
    }
Rebase the task spec time so that it is not earlier than the current time.
This is only needed for tasks passed in with --exec.  Normally, the
controller rebases the task spec time.
trogdor/src/main/java/org/apache/kafka/trogdor/agent/Agent.java