added methods for support ValueProvider in MqttIO

[twosom]

Please add a meaningful description for your change here
fixes #19378

This PR contains thease changes

• add ValueProvider methods for MqttIO.ConnectionConfiguration

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[Abacn]

Hi, is there a requirement in your use case that needs to serve ValueProvider? In the past ValueProviders were mainly used in Dataflow classic templates, which is superceded by flex templates that no longer need ValueProvider

[twosom]

Hi, is there a requirement in your use case that needs to serve ValueProvider? In the past ValueProviders were mainly used in Dataflow classic templates, which is superceded by flex templates that no longer need ValueProvider

@Abacn
Hello, thank you for your comment.
We are still using the classic template with ValueProvider and we are planning to move to the flex template in the future.
In my opinion, once we use flex templates, we may not need ValueProviders, but it would be nice to at least give users the option to use the existing classic templates.

[robertwb]

Now that we have flex templates, we prefer not propagating the ValueProvider boilerplate elsewhere without good reason, and advise flex templates for any template use that uses non-ValueProvider-enabled features. Is there a reason you cannot use flex templates?

[twosom]

Now that we have flex templates, we prefer not propagating the ValueProvider boilerplate elsewhere without good reason, and advise flex templates for any template use that uses non-ValueProvider-enabled features. Is there a reason you cannot use flex templates?

Flex templates require a Docker image to be built, which is more complex than uploading a JAR file to Google Storage. For our company, it's easier to upload the classic templates with a single Gradle task than to use the artifact registry.

[twosom]

This may be specific to our company. I can't guarantee it's the same for other companies.
I agree that we shouldn't propagate ValueProviders without a good reason.
I'll close the PR for now, but I still think users should have a choice.

[robertwb]

Now that we have flex templates, we prefer not propagating the ValueProvider boilerplate elsewhere without good reason, and advise flex templates for any template use that uses non-ValueProvider-enabled features. Is there a reason you cannot use flex templates?

Flex templates require a Docker image to be built, which is more complex than uploading a JAR file to Google Storage. For our company, it's easier to upload the classic templates with a single Gradle task than to use the artifact registry.

This is good feedback. My reading of https://cloud.google.com/dataflow/docs/guides/templates/using-flex-templates#build-template is that you don't have to build the docker image yourself, just provide the jar and other metadata (just like classic templates). Hopefully it shouldn't be too hard to package this gcloud command in a gradle task directly.

[twosom]

Now that we have flex templates, we prefer not propagating the ValueProvider boilerplate elsewhere without good reason, and advise flex templates for any template use that uses non-ValueProvider-enabled features. Is there a reason you cannot use flex templates?

Flex templates require a Docker image to be built, which is more complex than uploading a JAR file to Google Storage. For our company, it's easier to upload the classic templates with a single Gradle task than to use the artifact registry.

This is good feedback. My reading of https://cloud.google.com/dataflow/docs/guides/templates/using-flex-templates#build-template is that you don't have to build the docker image yourself, just provide the jar and other metadata (just like classic templates). Hopefully it shouldn't be too hard to package this gcloud command in a gradle task directly.

@robertwb
Thanks for sharing this article.
It will help my team migrate to Flex Templates.