ZOOKEEPER-3659 Make WatchManagerFactory log more readable

[rabi-kumar]

According to ticket ZOOKEEPER-3659 we need to make WatchManagerFactory more readable. For this I have made the following changes:

• Introduce a parameter in createWatchManager
• Use the passed parameter in logger of WatchManagerFactory
• Make necessary changes in DataTree, WatchManagerFactoryTest

Please do let me know if made changes makes sense or if I missed anything else so that additional changes could be made.

[rabi-kumar]

@maoling Calling for review.

[anmolnar]

Is it possible to use different WatchManagers for child and data watches?

[maoling]

@anmolnar

Is it possible to use different WatchManagers for child and data watches?

Could you please give us more context?
@ravowlga123
I found another similar issue(ZOOKEEPER-3722 you may also interested in :)

[anmolnar]

@maoling Currently the config options don't allow using different watch managers for child and data watcher. Hence I don't see the point of logging them separately.

[maoling]

• Yes, child and data watcher cannot set different watchManager
• the problem is that the absolutely same log prints twice which will confuse users. If we don't logging them separately, we can make the log only print one time? e.g.

    public static String watchManagerName;
    static {
        watchManagerName = System.getProperty(ZOOKEEPER_WATCH_MANAGER_NAME);
        if (watchManagerName == null) {
            watchManagerName = WatchManager.class.getName();
        }
        LOG.info("Using {} as watch manager", watchManagerName);
    }
    public static IWatchManager createWatchManager() throws IOException {

@anmolnar WDYT?