4.0.6 release notes

(cherry picked from commit e413907)

Author: michaelklishin

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+## RabbitMQ 4.0.6
+
+RabbitMQ `4.0.6` is a maintenance release in the `4.0.x` [release series](https://www.rabbitmq.com/release-information).
+
+Starting June 1st, 2024, community support for this series will only be provided to [regularly contributing users](https://github.com/rabbitmq/rabbitmq-server/blob/main/COMMUNITY_SUPPORT.md) and those
+who hold a valid [commercial support license](https://tanzu.vmware.com/rabbitmq/oss).
+
+It is **strongly recommended** that you read [4.0 release notes](https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.0.1)
+in detail if upgrading from a version prior to `4.0.0`.
+
+
+### Minimum Supported Erlang Version
+
+This release requires Erlang 26 and supports Erlang versions up to `27.2.x`.
+[RabbitMQ and Erlang/OTP Compatibility Matrix](https://www.rabbitmq.com/docs/which-erlang) has more details on
+Erlang version requirements for RabbitMQ.
+
+Nodes **will fail to start** on older Erlang releases.
+
+
+## Changes Worth Mentioning
+
+Release notes can be found on GitHub at [rabbitmq-server/release-notes](https://github.com/rabbitmq/rabbitmq-server/tree/v4.0.x/release-notes).
+
+### Core Broker
+
+#### Bug Fixes
+
+ * When a quorum queue leader has changed, followers were not always notified of
+   unapplied [for/by them] log commands.
+
+   GitHub issue: [#13095](https://github.com/rabbitmq/rabbitmq-server/pull/13095)
+
+ * Default cluster formation timeout with [Khepri](https://www.rabbitmq.com/docs/metadata-store) now matches that of Mnesia (5 minutes by default).
+
+   Discovered and reported by @evolvedlight.
+
+   GitHub issue: [#13195](https://github.com/rabbitmq/rabbitmq-server/pull/13195)
+
+ * When stream consumer was cancelled, an [internal event]() was not emitted.
+
+   GitHub issues: [#13085](https://github.com/rabbitmq/rabbitmq-server/pull/13085), [#9356](https://github.com/rabbitmq/rabbitmq-server/pull/9356), [#13097](https://github.com/rabbitmq/rabbitmq-server/pull/13097)
+
+ * Stream consumer metrics were not cleared when its respective connection was closed.
+
+   GitHub issue: [#13086](https://github.com/rabbitmq/rabbitmq-server/pull/13086)
+
+ * Quorum queues could return a list of members (replicas) with duplicates in some cases.
+
+   GitHub issue: [#13168](https://github.com/rabbitmq/rabbitmq-server/pull/13168)
+
+ * Classic queues with priorities could run into an exception.
+
+   GitHub issue: [#13088](https://github.com/rabbitmq/rabbitmq-server/pull/13088)
+
+ * Corrected a log message.
+
+   GitHub issue: [#13155](https://github.com/rabbitmq/rabbitmq-server/pull/13155)
+
+#### Enhancements
+
+ * A new mechanism for protecting a virtual host from deletion using metadata.
+
+   GitHub issues: [#12772](https://github.com/rabbitmq/rabbitmq-server/issues/12772), [#13017](https://github.com/rabbitmq/rabbitmq-server/pull/13017)
+
+
+### CLI Tools
+
+#### Bug Fixes
+
+ * `rabbitmqctl import_definitions` hanged when definitions were provided via the standard input
+    instead of a file.
+
+    GitHub issue: [#13157](https://github.com/rabbitmq/rabbitmq-server/issues/13157)
+
+#### Enhancements
+
+ * [`rabbitmqadmin` v2](https://www.rabbitmq.com/docs/management-cli) has matured enough to recommend
+   it over the original version of the tool
+
+ * `rabbitmq-diagnostics ` CLI documentation was improved to clarify that all certificates
+   discovered will be checked for expiration.
+
+   GitHub issue: [#13038](https://github.com/rabbitmq/rabbitmq-server/pull/13038)
+
+ * New health checks for [metadata store](https://www.rabbitmq.com/docs/metadata-store) initialization:
+
+   1. `rabbitmq-diagnostics check_if_metadata_store_is_initialized`
+   2. `rabbitmq-diagnostics check_if_metadata_store_is_initialized_with_data`
+
+   GitHub issue: [#13169](https://github.com/rabbitmq/rabbitmq-server/pull/13169)
+
+
+### Prometheus Plugin
+
+#### Bug Fixes
+
+ * Improved metric description.
+
+   GitHub issue: [#13178](https://github.com/rabbitmq/rabbitmq-server/pull/13178)
+
+
+### Management Plugin
+
+#### Bug Fixes
+
+ * Pagination-related sections of the HTTP API reference were clarified to explain
+   that the maximum page size cannot exceed 500.
+
+   GitHub issue: [#13042](https://github.com/rabbitmq/rabbitmq-server/issues/13042)
+
+ * Empty `channel_details` objects are now serialized as empty objects and not empty arrays.
+
+   GitHub issue: [#13091](https://github.com/rabbitmq/rabbitmq-server/pull/13091)
+
+#### Enhancements
+
+ * New health checks for [metadata store](https://www.rabbitmq.com/docs/metadata-store) initialization:
+
+   1. GET `/api/health/checks/metadata-store/initialized`
+   2. GET `/api/health/checks/metadata-store/initialized/with-data`
+
+   GitHub issue: [#13169](https://github.com/rabbitmq/rabbitmq-server/pull/13169)
+
+#### Deprecations
+
+ * The original HTTP API One True Health Check™ is now a no-op. A comparable "mega health check"
+   has long been deprecated in CLI tools and was made a no-op in `4.0.0`.
+
+   This endpoint was using a [deprecated feature](https://www.rabbitmq.com/docs/deprecated-features): a classic non-exclusive transient (non-durable) queue.
+
+   See [Health Checks](https://www.rabbitmq.com/docs/monitoring#health-checks) for modern focused alternatives.
+
+   GitHub issue: [#13047](https://github.com/rabbitmq/rabbitmq-server/issues/13047)
+
+
+### Peer Discovery Consul Plugin
+
+#### Enhancements
+
+ * `` is a new configuration setting that allows the backend to skip registration.
+
+   This is useful when Consul is used for peer discovery but a different tool such as Nomad
+   is used to keep track of the services and their registration, unregistration.
+
+   Contributed by @frederikbosch.
+
+   GitHub issue: [#13201](https://github.com/rabbitmq/rabbitmq-server/pull/13201)
+
+
+### Erlang AMQP 1.0 Client
+
+#### Bug Fixes
+
+ * Purging an non-existing queue now returns a 404 response.
+
+   GitHub issue: [#13148](https://github.com/rabbitmq/rabbitmq-server/pull/13148)
+
+
+### Dependency Changes
+
+ * `ra` was upgraded to [`2.15.1`](https://github.com/rabbitmq/ra/releases)
+ * `observer_cli` was upgraded to [`1.8.2`](https://github.com/zhongwencool/observer_cli/releases)
+
+
+## Source Code Archives
+
+To obtain source code of the entire distribution, please download the archive named `rabbitmq-server-4.0.6.tar.xz`
+instead of the source tarball produced by GitHub.