RFR: 8177418: NPE is not apparent for methods in java.util.TimeZone API docs [v2]

[Justin Lu]

> When their input is null, the following methods in java.util.TimeZone throw a NullPointerException:
> 
> TimeZone.getTimeZone(String ID)
> TimeZone.setID(String ID)
> TimeZone.inDaylightTime(Date date)
> 
> For example, 
> 
> 
> String someID = null;
> TimeZone tz1 = TimeZone.getTimeZone(someID);
> ``` 
> 
> throws a `NullPointerException`
> 
> However this is not documented in the API docs in the form of a _throws:_ section.
> 
> This change updates the documentation to make this apparent.

Justin Lu has updated the pull request incrementally with two additional commits since the last revision:

 - Document inDaylightTime
 - Document setID

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/11888/files
  - new: https://git.openjdk.org/jdk/pull/11888/files/19bd4fae..415ec9f4

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11888&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11888&range=00-01

  Stats: 2 lines in 1 file changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/11888.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11888/head:pull/11888

PR: https://git.openjdk.org/jdk/pull/11888