[hitless upgrade] Support for none moving-endpoint-type in maintenance event notifications (CAE-1285)

[ggivo]

Description:

This change extends Lettuce’s support for Redis maintenance event notifications by adding the none option for moving-endpoint-type when enabling maintenance events.

According to the specification, moving-endpoint-type determines whether the MOVING push message contains an internal/external IP or FQDN.
The new special value none indicates that the MOVING message should not contain any endpoint; instead, the endpoint field is null.

When the client receives a MOVING message with moving-endpoint-type=none, it will schedule a graceful reconnect to the currently configured endpoint after half of the grace period specified in the message has elapsed.

Summary of changes:

• Added support for moving-endpoint-type=none option in CLIENT MAINT_NOTIFICATIONS.
• Implemented delayed rebind behavior: reconnect is scheduled after half of the grace period when none is used.

Example to enable maintenance notifications with none

CLIENT MAINT_NOTIFICATIONS ON moving-endpoint-type none

Tested manually & unit test

Make sure that:

• You have read the contribution guidelines.
• You have created a feature request first to discuss your contribution intent. Please reference the feature request ticket number in the pull request.
• You applied code formatting rules using the mvn formatter:format target. Don’t submit any formatting related changes.
• You submit test cases (unit or integration tests) that back your changes.

[Copilot]

Pull Request Overview

This PR extends Lettuce's Redis maintenance event notifications to support the moving-endpoint-type=none option. When this option is used, the MOVING message doesn't contain an endpoint and triggers a graceful reconnect to the currently configured endpoint after half the grace period has elapsed.

• Added NONE enum value to AddressType with proper documentation
• Implemented deferred rebind logic that schedules reconnection after half the grace period
• Modified MOVING event parsing to handle null endpoints correctly

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
MaintenanceEventsOptions.java	Added NONE address type enum value with documentation
RedisHandshake.java	Added mapping for NONE address type to "none" string
MaintenanceAwareConnectionWatchdog.java	Implemented deferred rebind logic and null endpoint handling
MaintenanceAwareConnectionWatchdogUnitTests.java	Added test coverage for null endpoint scenario and refactored helper methods

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[tishun]

Looks good, thanks!