This commit removes the method AllocatedPersistentTask.getState() that
exposes the internal state of an AllocatedPersistentTask and replaces
it with a new isCompleted() method. Related to elastic#29608.

Clarify the “one minute” in the instructions to disable the shard allocation
when doing maintenance to say that it is configurable.

This change replaces some existing try-finally statements that close resources
in their finally block with the slightly shorter and safer try-with-resources
pattern.

Our API spec define the tasks API as e.g. tasks.list, meaning that they belong to their own namespace. This commit moves them from the cluster namespace to their own namespace.

Relates to elastic#29546

…28939)

The stored scripts API today accepts malformed requests instead of throwing an exception.
This PR deprecates accepting malformed put stored script requests (requests not using the official script format).

Relates to elastic#27612

)

This commit removes some log traces in AzureStorageServiceImpl and also
fixes the AzureStorageServiceTests so that is uses the real
implementation to create Azure clients.

We failed to register "aliases" and "version" into the list of keywords
in the IndexTemplateMetaData; then fail to parse the following index
template.

```
{
    "aliases": {"log": {}},
    "index_patterns": ["pattern-1"]
}
```
This commit registers that missing keywords.

Limits the scope of the runtime dependency on
BouncyCastle so that it can be eventually removed.

* Splits functionality related to reading and generating certificates
and keys in two utility classes so that reading certificates and
keys doesn't require BouncyCastle.
* Implements a class for parsing PEM Encoded key material (which also
adds support for reading PKCS8 encoded encrypted private keys).
* Removes BouncyCastle dependency for all of our test suites(except
for the tests that explicitly test certificate generation) by using
pre-generated keys/certificates/keystores.

This snapshot includes LUCENE-8328 which is needed to stabilize CCR builds.

Relates to elastic#23658

Currently AbstractHttpServerTransport is in a netty4 module. This is the
incorrect location. This commit moves it out of netty4 module.
Additionally, it moves unit tests that test AbstractHttpServerTransport
logic to server.

When subprocesses are started with ProcessBuilder, they're forked by the
java process directly rather than from a shell, which can be surprising
for our use case here in the packaging tests which is similar to
scripting.

This commit changes the tests to run their subprocess commands in a
shell, using the bash -c <script> syntax for commands on linux and using
the powershell.exe -Command <script> syntax for commands on windows.
This syntax on windows is essentially what the tests were already doing.

Applies default file and directory permissions to zip distributions
similar to how they're set for the tar distributions. Previously zip
distributions would retain permissions they had on the build host's
working tree, which could vary depending on its umask

For elastic#30799

* Make sure all instance variables are final.
* Make generateKey a private static method, instead of protected.
* Rename formatter -> format for consistency.
* Serialize bucket keys as strings as opposed to optional strings.
* Pull the stream serialization logic for buckets into the Bucket class.

ML has dedicated APIs for datafeeds and jobs yet base test classes and
some tests were relying on the cluster state for this state. This commit
removes this usage in favor of using the dedicated endpoints.

…ge was backported.

This commit renames methods in the PersistentTasksService, to 
make obvious that the methods send requests in order to change 
the state of persistent tasks. 

Relates to elastic#29608.

This commit also adds index_prefixes tests to TextFieldMapperTests to ensure that cloning and wire-serialization work correctly

This change adds a new option to the composite aggregation named `missing_bucket`.
This option can be set by source and dictates whether documents without a value for the
source should be ignored. When set to true, documents without a value for a field emits
an explicit `null` value which is then added in the composite bucket.
The `missing` option that allows to set an explicit value (instead of `null`) is deprecated in this change and will be removed in a follow up (only in 7.x).
This commit also changes how the big arrays are allocated, instead of reserving
the provided `size` for all sources they are created with a small intial size and they grow
depending on the number of buckets created by the aggregation:
Closes elastic#29380

With multiple data paths, we write the state files for index metadata to all data paths. We only properly fsync on the first location, though. For other locations, we possibly expose the file before its contents is properly fsynced. This can lead to situations where, after a crash, and where the first data path is not available anymore, ES will see a partially-written state file, preventing the node to start up.

AliasMetaData should be parsed more leniently so that the high-level REST client can support forward compatibility on it. This commit addresses this issue that was found as part of elastic#28799 and adds dedicated XContent tests as well.

…ic#30926)

When we are connecting to a remote cluster we should never select
dedicated master nodes as gateway nodes, or we will end up loading them
with requests that should rather go to other type of nodes e.g. data
nodes or coord_only nodes.

This commit adds the selection based on the node role, to the existing
selection based on version and potential node attributes.

Closes elastic#30687

Relates elastic#29465

Adds the synced flush API to the high level REST client.

Relates to elastic#27205.

They had some copy and paste errors that failed the docs build.

Currently failures to compile a script usually lead to a ScriptException, which
inherits the 500 INTERNAL_SERVER_ERROR from ElasticsearchException if it does
not contain another root cause. Instead, this should be a 400 Bad Request error.
This PR changes this more generally for script compilation errors by changing 
ScriptException to return 400 (bad request) as status code.

Closes elastic#12315

Fix serialization after backport

Relates elastic#29465

More cleanup of JDBC driver project

Relates to elastic#29856

Tracked by elastic#30970

This commit adds Verify Repository, the associated docs and tests for
the high level REST API client. A few small changes to the Verify
Repository Response went into the commit as well.

Relates elastic#27205

…#30961)

Add “took” timing info to response for _msearch/template API
Closes elastic#30957

We have identified the source causing these tests failed.
This commit mutes them again until we have a proper fix.

Relates elastic#29392

Tracked by elastic#30094

Replaces some occurances of Vector class with ArrayList in
tests of the rank-eval module.

This code is from an Apache 2.0 licensed codebase and when we imported
it into our codebase it carried the Apache 2.0 license as well. However,
during the migration of the X-Pack codebase from the internal private
repository to the elastic/elasticsearch repository, the migration tool
mistakently changed the license on this source file from the Apache 2.0
license to the Elastic license. This commit addresses this mistake by
reapplying the Apache 2.0 license.

Tracked by elastic#30982

This commit changes the isCompleted() method to be protected so that
classes that extends AllocatedPersistentTask can use it.

Related to elastic#30858

It can fail in either the mixed cluster or the upgraded cluster,
so it needs to be muted in both.

Tracked by elastic#30982

This commit reworks the Sniffer component to simplify it and make it possible to test it.

In particular, it no longer takes out the host that failed when sniffing on failure, but rather relies on whatever the cluster returns. This is the result of some valid comments from elastic#27985. Taking out one single host is too naive, hard to test and debug.

A new Scheduler abstraction is introduced to abstract the tasks scheduling away and make it possible to plug in any test implementation and take out timing aspects when testing.

Concurrency aspects have also been improved, synchronized methods are no longer required. At the same time, we were able to take elastic#27697 and elastic#25701 into account and fix them, especially now that we can more easily add tests.

Last but not least, unit tests are added for the Sniffer component, long overdue.

Closes elastic#27697
Closes elastic#25701

…ontext (elastic#30712)

This change deprecates completion queries and documents without context that target a
context enabled completion field. Querying without context degrades the search
performance considerably (even when the number of indexed contexts is low).
This commit targets master but the deprecation will take place in 6.x and the functionality
will be removed in 7 in a follow up.

Closes elastic#29222

This commit removes the RequestBuilder generic type from Action. It was
needed to be used by the newRequest method, which in turn was used by
client.prepareExecute. Both of these methods are now removed, along with
the existing users of prepareExecute constructing the appropriate
builder directly.

)

* Ensure that a purposefully wrong key is used

Uses a specific keypair for tests that require a purposefully wrong
keypair instead of selecting one randomly from the same pull from
which the correct one is selected. Entropy is low because of the
small space and the same key can be randomly selected as both the
correct one and the wrong one, causing the tests to fail.
The purposefully wrong key is also used in 
testSigningKeyIsReloadedForEachRequest and needs to be cleaned
up afterwards so the rest of the tests don't use that for signing.

Resolves elastic#30970

Since master will always communicate with a >=6.4 node, the logic for
checking if the node is 6.4 and conditionally reading and writing based
on that can be removed from master. This logic will stay in 6.x as it is
the bridge to the cleaner response in master. This also unmutes the
failing test due to this bwc change.

Closes elastic#30807

This modifies the high level rest client to allow calling code to
customize per request options for the bulk API. You do the actual
customization by passing a `RequestOptions` object to the API call
which is set on the `Request` that is generated by the high level
client. It also makes the `RequestOptions` a thing in the low level
rest client. For now that just means you use it to customize the
headers and the `httpAsyncResponseConsumerFactory` and we'll add
node selectors and per request timeouts in a follow up.

I only implemented this on the bulk API because it is the first one
in the list alphabetically and I wanted to keep the change small
enough to review. I'll convert the remaining APIs in a followup.

Although elasticsearch-certutil generates PKCS#12
files which are usable as both keystore and truststore
this is uncommon in practice. Settle these expectations
for the users following our security guides.

This is related to elastic#30141. Right now in the transport client we open a
temporary node connection and take the node information. This node
information is used to open a permanent connection that is used for the
client. However, we continue to use the configured transport address.
If the configured transport address is a load balancer, you might
connect to a different node for the permanent connection. This causes
the handshake validation to fail. This commit removes the handshake
validation for the transport client when it simple node sample mode.

* Remove MappedFieldType#nullValueQuery, as it is now unused.
* Remove MappedFieldType#queryStringTermQuery, as it is never overridden.

* Retain the expiryDate for trial licenses

While updating the license signature to the new license spec retain
the trial license expiration date to that of the existing license.

Resolves elastic#30882

Changes watcher's integration tests to wait 30 seconds when starting
watcher rather than 10 seconds because this build failed when starting
took 12 seconds:
https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+6.3+periodic/222/console