RFR: 8332015: Add `@since` tags to jdk.httpserver [v2]

[Nizar Benalla]

> Please review this simple change, aiming to fix current uses of `@since` in the source code
> -The constructor BasicAuthenticator(java.lang.String,java.nio.charset.Charset) needs an `@since 14` instead of 9.
> -com.sun.net.httpserver.spi: package-info.java does not contain an `@since`.
> Thanks in advance.

Nizar Benalla has updated the pull request incrementally with one additional commit since the last revision:

  fix copyright headers

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/19168/files
  - new: https://git.openjdk.org/jdk/pull/19168/files/d35d602f..363bcf94

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19168&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19168&range=00-01

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/19168.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19168/head:pull/19168

PR: https://git.openjdk.org/jdk/pull/19168