[BEAM-6493] Convert the WordCount samples to Kotlin

[harshithdwivedi]

This PR converts the WordCounts sample from Java to Kotlin.
Please have a look and let me know if any changes are required.
@kennknowles @pabloem

I made this new PR since there have been some 2FA issues with my earlier GitHub Account (@the-dagger) and I'm locked out of it for the time being.

P.S. I haven't converted all the tests to Kotlin yet; I'll do that once all the source classes are migrated

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Post-Commit Tests Status (on master branch)

Lang	SDK	Apex	Dataflow	Flink	Gearpump	Samza	Spark
Go		---	---	---	---	---	---
Java
Python		---			---	---	---

See .test-infra/jenkins/README for trigger phrase, status and link of all Jenkins jobs.

[harshithdwivedi]

@kennknowles The Java Precommit test is failing here, can you help me debug why that's the case?

[pabloem]

If you open the "details" of the precommit run, you can see what Jenkins says. Here is some stuff:

By the look of it, some Java warnings. You can also look at the Gradle Build Scan. Where you'll see some kotlin-related tasks failed

Here are the errors from the compile /test task for the examples: https://scans.gradle.com/s/sklwyla23gpbq/console-log?task=:beam-examples-kotlin:compileTestJava#L15

Gradle builds ask for emails, but they provide a lot of value : ) I recommend you check it out.

[pabloem]

@harshithdwivedi lmk if I can help

[harshithdwivedi]

Hi @pabloem I was out travelling for the last week so sorry for the inactivity here.
I'm working on this as we speak and should send out a fix that solves the build errors by eod.

I'll let you know in case I stumble upon any issue; thanks!

[pabloem]

No need to apologize : ) I just didn't want you to forget about thisw, because we're grateful for the contribution.
Sorry about the spotless trouble. You can run ./gradlew :beam-examples-kotlin:spotlessApply to do the autoformatting.

[harshithdwivedi]

@pabloem Looks like all the tests have finally passed 😅
LMK if you need me to squash the commits.

[kennknowles]

You should find a link to the Gradle scan on the Jenkins results page for the build.

[kennknowles]

The errors are caused by a recent change that moved things around inside the sdk.util package into sdk.util.gcp. If you rebase your PR again master you will get the errors and they will be easy to fix, just an import change.

:beam-examples-kotlin:compileKotlin FAILED
--
e: /home/jenkins/jenkins-slave/workspace/beam_PreCommit_Java_Commit/src/examples/kotlin/src/main/java/org/apache/beam/examples/kotlin/common/ExampleUtils.kt: (38, 33): Unresolved reference: RetryHttpRequestInitializer
e: /home/jenkins/jenkins-slave/workspace/beam_PreCommit_Java_Commit/src/examples/kotlin/src/main/java/org/apache/beam/examples/kotlin/common/ExampleUtils.kt: (40, 33): Unresolved reference: Transport
e: /home/jenkins/jenkins-slave/workspace/beam_PreCommit_Java_Commit/src/examples/kotlin/src/main/java/org/apache/beam/examples/kotlin/common/ExampleUtils.kt: (351, 21): Unresolved reference: Transport
e: /home/jenkins/jenkins-slave/workspace/beam_PreCommit_Java_Commit/src/examples/kotlin/src/main/java/org/apache/beam/examples/kotlin/common/ExampleUtils.kt: (352, 21): Unresolved reference: Transport
e: /home/jenkins/jenkins-slave/workspace/beam_PreCommit_Java_Commit/src/examples/kotlin/src/main/java/org/apache/beam/examples/kotlin/common/ExampleUtils.kt: (357, 29): Unresolved reference: RetryHttpRequestInitializer
e: /home/jenkins/jenkins-slave/workspace/beam_PreCommit_Java_Commit/src/examples/kotlin/src/main/java/org/apache/beam/examples/kotlin/common/ExampleUtils.kt: (365, 21): Unresolved reference: Transport
e: /home/jenkins/jenkins-slave/workspace/beam_PreCommit_Java_Commit/src/examples/kotlin/src/main/java/org/apache/beam/examples/kotlin/common/ExampleUtils.kt: (366, 21): Unresolved reference: Transport
e: /home/jenkins/jenkins-slave/workspace/beam_PreCommit_Java_Commit/src/examples/kotlin/src/main/java/org/apache/beam/examples/kotlin/common/ExampleUtils.kt: (371, 29): Unresolved reference: RetryHttpRequestInitializer

[kennknowles]

You can see the changes in #8217 and also the changes to the Java WordCount. Sorry for this mix up!

[harshithdwivedi]

Looks like I messed up on my end while rebasing the PR.
I've created a fresh one incorporating the changes relevent to the Issue.
#8291