Feat: Add SNS FIFO Topic support

[codingtim]

Fixes #41

📢 Type of change

• Bugfix
• New feature
• Enhancement
• Refactoring

📜 Description

This pull requests add support for FIFO SNS publishRequest. #41
The implementation is based on QueueMessageChannel.

💡 Motivation and Context

SNS added FIFO topics which require a mandatory MessageGroupId when publishing messages.
Without this change it is not possible to use spring-cloud-aws to publish messages to SNS FIFO topics.

💚 How did you test it?

Unit tests were added.

📝 Checklist

• I reviewed submitted code
• I added tests to verify changes
• I updated reference documentation to reflect the change
• All tests passing
• No breaking changes

🔮 Next steps

[alex-ninetynine]

Shouldn't this value be the same as the SQS headers in SqsMessageHeaders.java?

Suggested change

	public static final String MESSAGE_GROUP_ID_HEADER = "MessageGroupId";
	public static final String MESSAGE_GROUP_ID_HEADER = "message-group-id";

[codingtim]

You are correct that this does not follow the naming of SqsMessageHeaders. I followed the AWS header naming. I do not see added value in adding another translation layer which is confusing to users?
I also understand the need for consistency so maintainer can say which is preferred :)

[maciejwalkowiak]

I would be in for keeping consistency with AWS naming, but since SQS has been implemented already like that 4 years ago, lets keep it in sync with SQS implementation.

We can reconsider for 3.0

[alex-ninetynine]

Same as before

Suggested change

	public static final String MESSAGE_DEDUPLICATION_ID_HEADER = "MessageDeduplicationId";
	public static final String MESSAGE_DEDUPLICATION_ID_HEADER = "message-deduplication-id";

[codingtim]

@maciejwalkowiak can you have a look at the first remark of Alex and say which value should be used for the headers? Then I update the PR so it can be merged for an upcoming release?

[maciejwalkowiak]

@codingtim thanks for the PR! Are you also able to update the reference docs? It would be great to add a section explaining how to use FIFO SNS topics.

[codingtim]

@maciejwalkowiak reference docs are updated to include FIFO SNS topic

[birnbuazn]

Any news on this? Unfortunately Spring Cloud AWS seems to be moving very slowly. This is becoming more and more of a show stopper for us, because we are already waiting for 2 PRs to be approved and merged.

[maciejwalkowiak]

@birnbuazn we're working now towards release. It does move slower than we wish, we are working on finding more time to work on the project.