tidy up some licence header issues

Some of the java source files have ASL v2 licence headers with various inconsistencies, e.g a bunch use javadocs while the majority use comments as expected. Some of those javadocs have <p> elements in them, some dont. There are a variety of indentations. A tiny number even use the regular version of the header rather than the ASF variant they should. A few even have Copyright ASF attributions they shouldnt.

These variations are annoying as people often copy and paste from files in the area they are working when making changes, meaning if they source one of these existing files then the problems invariably either spread if not noticed in review, or cause unnecessary review cycles if they are. We should fix up all the obvious instances to use the standard ASF version of the ASL v2 header text and thus avoid this.