[Task]: Normalize Beam YAML PubSub format to uppercase

[ffernandez92]

What needs to happen?

The current PubSub YAML implementation has the format option in lowercase. However, Kafka and PubSub Lite have it in uppercase. I'd like to change the current PubSub one to accept uppercase and grandfather in the existing uses.

Issue Priority

Priority: 3 (nice-to-have improvement)

Issue Components

• Component: Python SDK
• Component: Java SDK
• Component: Go SDK
• Component: Typescript SDK
• Component: IO connector
• Component: Beam YAML
• Component: Beam examples
• Component: Beam playground
• Component: Beam katas
• Component: Website
• Component: Spark Runner
• Component: Flink Runner
• Component: Samza Runner
• Component: Twister2 Runner
• Component: Hazelcast Jet Runner
• Component: Google Cloud Dataflow Runner

[ffernandez92]

.take-issue

[ffernandez92]

@robertwb what do you think about the PR? It aims to standardize the uppercase-lowercase issue with PubSub (Since Kafka and PSL use uppercase). For now, it will accept both until we're ready to deprecate the lowercase one. I've already implemented a warning log for the usage of lowercase

cc: @brucearctor

[brucearctor]

Marking as closed. There is likely an eventual follow up task to actually standardize, instead of allowing both. But, can revisit that in MANY versions from now.