[jdk21u-dev] RFR: 8335181: Incorrect handling of HTTP/2 GOAWAY frames in HttpClient

[Alexey Bakhtin]

Please review the backport of JDK-8335181

src/java.net.http/share/classes/jdk/internal/net/http/MultiExchange.java
 - manual merge for MultiExchange::getExceptionalCF
because of the difference in the logging caused by 8310330

src/java.net.http/share/classes/jdk/internal/net/http/Http2Connection.java
- added import for the AtomicLong class manually because of the difference in the import section

src/java.net.http/share/classes/jdk/internal/net/http/ExchangeImpl.java
- copyright year updated manually

test/jdk/java/net/httpclient/lib/jdk/httpclient/test/lib/http2/Http2TestServerConnection.java
- import section is updated manually

test/jdk/java/net/httpclient/lib/jdk/httpclient/test/lib/common/HttpServerAdapters.java
- getConnectionKey() declaration is added manually in the HttpServerAdapters::HttpTestExchange class

All jtreg tests for java.net.httpclient are passed

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Depends on: https://git.openjdk.org/jdk21u-dev/pull/1416

Commit messages:
 - Backport 720b44648bcff997278af92746f942b2425298a5

Changes: https://git.openjdk.org/jdk21u-dev/pull/1417/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1417&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8335181
  Stats: 625 lines in 12 files changed: 571 ins; 2 del; 52 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1417.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1417/head:pull/1417

PR: https://git.openjdk.org/jdk21u-dev/pull/1417