RFR : 8008632 : Additional JavaDoc tags @apiNote, @implSpec and @implNote for JDK API Docs

[Mike Duigou]

Hello All;

Some of you have noticed that the lambda streams libraries patches currently going in to the TL repo make use of special javadoc tags. There are three tags being used:

@apiNote : Non-normative notes about the API. Usually used for examples.
@implSpec : Describes required behaviour of conforming implementations. Key is that the description is not inherited.
@implNote : Non-normative notes about the implementation. Typically used for descriptions of the behaviour. Also not inherited.

The tags are used primarily by default method implementations but will be used elsewhere as well. 

These tags are enabled by use of the -tag feature on the javadoc tool command line. They are not proposed as standard javadoc tags and may be implemented differently in future Java releases. Since they are implemented as custom tags just for the JDK API documentation you can't automatically use them in your own code. (You can, of course, add the same command line options to your javadoc invocations if you like these tags).

http://cr.openjdk.java.net/~mduigou/JDK-8008632/0/webrev/

The patch enumerates the new custom tags in addition to the standard tags to ensure correct output order.