[improve][client] Add optional fields to dead letter policy for configuring batching/chunking

[rindavis]

Fixes #20934
PIP 293

Motivation

We encountered an issue when chunked messages had to be retried, like

org.apache.pulsar.client.api.PulsarClientException$InvalidMessageException: The producer mdl-pulsar-0-12 of the topic part-v1 sends a message with 7094331 bytes that exceeds 5242880 bytes

because retry letter and dead letter producers never enable chunking. Our chunked messages may be very large, so simply increasing the maximum is probably not a good option.

This change allows the client to set if they want chunking and batching for these produces. The properties are separated in retry letter and dead letter, since currently the retry letter disables batching while the dead letter enables it implicitly. (So, we did not want a single pair of new properties to always set them to the same value.)

Modifications

Edited the DeadLetterPolicy to add these new fields, and the ConsumerImpl to pick them up in the consumer and when creating the producers.

Verifying this change

• Make sure that the change passes the CI checks.

This change added tests and can be verified as follows:

• Added unit test for setting the new fields, including one checking the defaults

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

We may want to update the Java client documentation to reflect these new options.

Matching PR in forked repository

PR in forked repository: rindavis#1

[rindavis]

We added 4 new properties instead of just 2 because the current settings in ConsumerImpl (next file in change set) have batching set to false for retry letter and to true (by default) for dead letter. Thus we did not want a single setting to have to be shared between both producers.

[RobertIndie]

We need a PIP before merging this PR.

[RobertIndie]

We couldn't enable the batching and chunking at the same time. This will throw an exception when initializing the retryLetterProducer:

pulsar/pulsar-client/src/main/java/org/apache/pulsar/client/impl/ProducerBuilderImpl.java

Lines 96 to 97 in 0214745

	checkArgument(!(conf.isBatchingEnabled() && conf.isChunkingEnabled()),
	"Batching and chunking of messages can't be enabled together");

[rindavis]

Corrected the test case. Do we need to add validation somewhere else in this changeset, or is having it in the ProducerBuilderImpl enough?

[RobertIndie]

IMO, we shouldn't expose these configurations to DeadLetterPolicy. This will introduce some producer concepts to the consumer.

[jackson-chris]

Can you educate me on why a PIP is required for this change? This is a defect of existing implementation and thus not a new feature and as far as I can tell not a big change.

[RobertIndie]

Can you educate me on why a PIP is required for this change? This is a defect of existing implementation and thus not a new feature and as far as I can tell not a big change.

This PR adds new configurations to the DeadLetterPolicy which is a part of public API. Therefore it introduces a new feature. Any changes to the public API should require a PIP.