…4426)

[Netty 4.1.111.Final](https://netty.io/news/2024/06/11/4-1-111-Final.html) contains important fixes:
- netty/netty#14086
- netty/netty#14093

On the Pulsar side these address Broker stability when TLS with Bookkeeper V2 protocol is used between Broker and Bookies. The Bookkeeper client didn't contain a workaround for the Netty SslHandler "feature" like Pulsar did. That's why Bookkeeper client was impacted. Netty 4.1.111.Final will address those stability issues with the Bookkeeper client when using V2 protocol over TLS.

- Upgrade Netty to 4.1.111.Final
- Switch to use grpc-netty-shaded instead of grpc-netty
  - grpc-java is not compatible with Netty 4.1.111.Final. [grpc-java supports only specific Netty versions](https://github.com/grpc/grpc-java/blob/master/SECURITY.md#netty). The solution is to use grpc-netty-shaded instead of grpc-netty dependency.
- Add module to shade jetcd-core partially so that it can work with grpc-netty-shaded.
  - jetcd-core library and it's transient dependency vertx-grpc has a direct dependency on grpc-netty and it doesn't work with grpc-netty-shaded without this solution.
  - this solution avoids the need to shade grpc libraries completely which would cause a lot of duplication and increase build times.

(cherry picked from commit a95f698)

…4426)

[Netty 4.1.111.Final](https://netty.io/news/2024/06/11/4-1-111-Final.html) contains important fixes:
- netty/netty#14086
- netty/netty#14093

On the Pulsar side these address Broker stability when TLS with Bookkeeper V2 protocol is used between Broker and Bookies. The Bookkeeper client didn't contain a workaround for the Netty SslHandler "feature" like Pulsar did. That's why Bookkeeper client was impacted. Netty 4.1.111.Final will address those stability issues with the Bookkeeper client when using V2 protocol over TLS.

- Upgrade Netty to 4.1.111.Final
- Switch to use grpc-netty-shaded instead of grpc-netty
  - grpc-java is not compatible with Netty 4.1.111.Final. [grpc-java supports only specific Netty versions](https://github.com/grpc/grpc-java/blob/master/SECURITY.md#netty). The solution is to use grpc-netty-shaded instead of grpc-netty dependency.
- Add module to shade jetcd-core partially so that it can work with grpc-netty-shaded.
  - jetcd-core library and it's transient dependency vertx-grpc has a direct dependency on grpc-netty and it doesn't work with grpc-netty-shaded without this solution.
  - this solution avoids the need to shade grpc libraries completely which would cause a lot of duplication and increase build times.

(cherry picked from commit a95f698)

…pache#4426)

### Motivation

[Netty 4.1.111.Final](https://netty.io/news/2024/06/11/4-1-111-Final.html) contains important fixes:
- netty/netty#14086
- netty/netty#14093

On the Pulsar side these address Broker stability when TLS with Bookkeeper V2 protocol is used between Broker and Bookies. The Bookkeeper client didn't contain a workaround for the Netty SslHandler "feature" like Pulsar did. That's why Bookkeeper client was impacted. Netty 4.1.111.Final will address those stability issues with the Bookkeeper client when using V2 protocol over TLS.

### Changes

- Upgrade Netty to 4.1.111.Final
- Switch to use grpc-netty-shaded instead of grpc-netty
  - grpc-java is not compatible with Netty 4.1.111.Final. [grpc-java supports only specific Netty versions](https://github.com/grpc/grpc-java/blob/master/SECURITY.md#netty). The solution is to use grpc-netty-shaded instead of grpc-netty dependency.
- Add module to shade jetcd-core partially so that it can work with grpc-netty-shaded. 
  - jetcd-core library and it's transient dependency vertx-grpc has a direct dependency on grpc-netty and it doesn't work with grpc-netty-shaded without this solution.
  - this solution avoids the need to shade grpc libraries completely which would cause a lot of duplication and increase build times.

### Motivation

There is a potential jar shading issue introduced in #4426 that causes `NoClassDefFoundError` when connecting to an etcd metadata store.

The `jetcd-core-shaded` module was introduced in #4426 to address the compatibility issues between jetcd-core’s grpc-java dependency and Netty. You can find more details [here][1] and in the [grpc-java documentation][2].

[1]: #4426 (comment)
[2]: https://github.com/grpc/grpc-java/blob/master/SECURITY.md#netty

Currently, we use `unpack-shaded-jar` execution unpacks the shaded jar produced by `maven-shade-plugin:shade` into the `jetcd-core-shaded/target/classes` directory. However, the classes in this directory conflict with its dependencies. If the `maven-shade-plugin:shade` runs again without cleaning this directory, it can produce an incorrect shaded jar. You can replicate and verify this issue with the following commands:
```shell
# Step 1: Clean the build directory
mvn clean

# Step 2: Perform an install and unpack the shaded jar into a directory.
# Verify the import statement for `io.netty.handler.logging.ByteBufFormat` in 
# `org/apache/pulsar/jetcd/shaded/io/vertx/core/net/NetClientOptions.class`. 
# The correct import should be: 
# `import io.grpc.netty.shaded.io.netty.handler.logging.ByteBufFormat;`.
mvn install
unzip $M2_REPO/org/apache/bookkeeper/metadata/drivers/jetcd-core-shaded/4.18.0-SNAPSHOT/jetcd-core-shaded-4.18.0-SNAPSHOT-shaded.jar \
  -d metadata-drivers/jetcd-core-shaded/target/first-classes

# Step 3: Run the install command again without cleaning.
# The unpacked jar from the previous step will persist in `target/classes`. 
# Unpack the shaded jar into a different directory (e.g., second-classes) and check the import.
# The incorrect import will be: 
# `import io.grpc.netty.shaded.io.grpc.netty.shaded.io.netty.handler.logging.ByteBufFormat;`.
mvn install
unzip $M2_REPO/org/apache/bookkeeper/metadata/drivers/jetcd-core-shaded/4.18.0-SNAPSHOT/jetcd-core-shaded-4.18.0-SNAPSHOT-shaded.jar \
  -d metadata-drivers/jetcd-core-shaded/target/second-classes

# Step 4: Use IntelliJ IDEA's "Compare Directories" tool to compare the `first-classes` 
# and `second-classes` directories. The differences in imports should become apparent.
```

We can remove the attach and unpack configurations, and it should work fine.

This issue has already been [reported][3] in apache/pulsar, and a similar [patch][patch] has addressed it.

[3]: apache/pulsar#23513
[patch]: apache/pulsar#23604