We do not validate the name is not null, and not empty. Even though it
never should be, we had a build failure where it appears that somehow
this did happen. We add some validation here, in case this really is
happening, we will have a more clear indication where this is coming
from, and of course, validation that name fits the implicit assumptions
that it is not null and not empty.

In bash, checking for whether an env variable exists uses the -z test,
against a stringified env var, so that the test is actually whether the
env var is empty, but not necessarily undefined. We use this to test
whether JAVA_HOME is set, to determine whether the bundled jdk should be
used. In windows, this test is an actual "undefined" check. This commit
brings the behavior on two systems in sync, opting to allow for an empty
JAVA_HOME in windows to indicate the bundled jdk should be used.

closes #55134

The pom files for our published artifacts are sent to maven central
during Elastic's release process, but we may not found out until then
that we have inadvertently broken the pom structure, as has happened
several times before. This commit adds validation of the pom file
specifically for the rules required by maven central.

The "old jdk" tests are just testing support for downloading from oracle
prior to java 12.0.1, when oracle added a hash to the url. This commit
moves these tests into the openjdk tests (ie oracle download tests),
since adoptopenjdk does not have any change in behavior that needs to be
tested.

If more than 100 shard-follow tasks are trying to connect to the remote 
cluster, then some of them will abort with "connect listener queue is 
full". This is because we retry on ESRejectedExecutionException, but not
on RejectedExecutionException.

After backporting #55337

)

Relates #55360

…55343)

We rewrite more query builders to MatchNoneQueryBuilders now, which are always
cacheable. We should make sure the tests expects this when the rewritten query
is a MatchNoneQueryBuilder.

Closes #55331

Implement the use of scalar functions inside aggregate functions.
This allows for complex expressions inside aggregations, with or without
GROUBY as well as with or without a HAVING clause. e.g.:

```
SELECT MAX(CASE WHEN a IS NULL then -1 ELSE abs(a * 10) + 1 END) AS max, b
FROM test
GROUP BY b
HAVING MAX(CASE WHEN a IS NULL then -1 ELSE abs(a * 10) + 1 END) > 5
```

Scalar functions are still not allowed for `KURTOSIS` and `SKEWNESS` as
this is currently not implemented on the ElasticSearch side.

Fixes: #29980
Fixes: #36865
Fixes: #37271

…oach for handling case insensitvity (#55294)

Closes #55288

Relates #55360

…55376)

Hotfix to not run into stuck snapshots because of master circuit breaking these requests.
Given that these requests are very small and much of the memory associated with them is already allocated
when the circuit breaker kicks in, the risk of this change introducing a higher chance of master running out
of memory should be very small.

Closes #54714

Relates #55378
Relates #55181

When a anomaly jobs, datafeeds, and analytics tasks are stopped, they enter an ephemeral state called `STOPPING`. 

If the node executing the task fails while this is occurring, they could be stuck in the limbo state of `STOPPING`. It is best to mark the tasks as completed if they get reassigned to a node.

Avoid repetition of the aggregation builder setup

Relates #55241

PR #51260 moved usage counts about mapping field types and analysis to
the `_cluster/stats` API.

This documents those stats in the response section of the cluster stats
API docs.

This fixes the long muted testHRDSplit. Some minor adjustments for modern day elasticsearch changes :). 

The cause of the failure is that a new `by` field entering the model with an exceptionally high count does not cause an anomaly. We have since stopped combining the `rare` and `by` in this manner. New entries in a `by` field are not anomalous because we have no history on them yet. 

closes #32966

This fixes two unreleased bugs:

1. Prediction value type of `number` might show unexpected classes

Analytics created models may have class labels like `1, 5, 10` (or some collection of discrete, whole numbers). These labels are passed to the inference model config in the `classification_labels` field.

When the predicted value format is `numeric` it should attempt to see if the classification labels are provided and are numeric. If so, use those. If not, use the underlying value.

2. When supplying an update overwrite, inference was losing the default prediction field value. This is because it was not copied over in the copy ctor in the ClassificationConfig.Builder class. 

closes #55332

We believe there's no longer a need to be able to disable basic-license
features completely using the "xpack.*.enabled" settings. If users don't
want to use those features, they simply don't need to use them. Having
such features always available lets us build more complex features that
assume basic-license features are present.

This commit deprecates settings of the form "xpack.*.enabled" for
basic-license features, excluding "security", which is a special case.
It also removes deprecated settings from integration tests and unit
tests where they're not directly relevant; e.g. monitoring and ILM are
no longer disabled in many integration tests.

This validates that if the winner v2 template is a global one, it doesn't specify the
index.hidden setting.

Relates #55396
Relates #53913

Enabled data streams and itv2 feature enabled system properties in server module's integ test task.

PR #54726 added java integration tests for data streams, so this is why these system properties
need to be enabled when running release build.