RFR: 8252767: URLConnection.setRequestProperty throws IllegalAccessError [v6]

[Jaikiran Pai]

> Can I please get a review and a sponsor for a fix for the issue reported at
> https://bugs.openjdk.java.net/browse/JDK-8252767?
> As noted in that issue, the `sun.net.www.URLConnection#setRequestProperty` is throwing a `IllegalAccessError` instead
> of a `IllegalStateException`. The commit here fixes that and includes a test which reproduces the issue and verifies
> the fix.  Would a CSR be needed for this change?

Jaikiran Pai has updated the pull request incrementally with one additional commit since the last revision:

  Use new TestNG Assert#assertThrows API

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/26/files
  - new: https://git.openjdk.java.net/jdk/pull/26/files/9b8539a1..0d5d961c

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=26&range=05
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=26&range=04-05

  Stats: 43 lines in 1 file changed: 3 ins; 34 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/26.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/26/head:pull/26

PR: https://git.openjdk.java.net/jdk/pull/26