docs(sample): Add sample for Native Image support in Pub/Sub

[mpeddada1]

This PR copies over the Pub/Sub sample, Setup Instructions and README for native image support from GoogleCloudPlatform/native-image-support-java. It also adds an integration test that can be run as a native image.

Calling mvn package -Pnative -DskipTests builds the native image for the application and calling mvn test -Pnative runs the test as a native image.

For more information: https://graalvm.github.io/native-build-tools/latest/maven-plugin.html#configuration

[anguillanneuf]

@mpeddada1 I'm seeing similar PRs for other products like googleapis/java-bigtable#1165 but I'm not aware of the context. Could you tell me a bit more about these samples?

[anguillanneuf]

Can someone tell me a bit more about this?

[mpeddada1]

@mpeddada1 I'm seeing similar PRs for other products but I'm not aware of the context. Could you tell me a bit more about these samples?

Thanks for the question! This is part of the work to move all native-image support related development away from the old native image support repository https://github.com/GoogleCloudPlatform/native-image-support-java into the googleapis/ org. To that end, as you may have noticed, we are trying to relocate all the samples from the old repo into the respective libraries in googleapis/.

[anguillanneuf]

Thanks @mpeddada1. One more question, who will be responsible for updating these samples? I don't mean the pom.xml but the samples themselves. At some point they will become outdated.

[mpeddada1]

Thanks @mpeddada1. One more question, who will be responsible for updating these samples? I don't mean the pom.xml but the samples themselves. At some point they will become outdated.

That's a good question @anguillanneuf! We'll maintain any parts of the sample that are native-image/GraalVM specific or require any knowledge of GraalVM (such as the setup instructions, addressing any issues related to Native Image compilation, keeping the GraalVM versions up-to-date). However, library maintainers would be better suited to address more product-specific aspects.