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.
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 #27205
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 #29546
Adding headers rather than setting them all at once seems more
user-friendly and we already do it in a similar way for parameters
(see Request#addParameter).
This commit adds Delete Repository, the associated docs and tests for
the high level REST API client. It also cleans up a seemingly innocuous
line in the RestDeleteRepositoryAction and some naming in SnapshotIT.
Relates #27205
This change adds a `listTasks` method to the high level java
ClusterClient which allows listing running tasks through the
task management API.
Related to #27205
This commit adds Create Repository, the associated docs and tests
for the high level REST API client. A few small changes to the
PutRepository Request and Response went into the commit as well.
This commit changes the default out-of-the-box configuration for the
number of shards from five to one. We think this will help address a
common problem of oversharding. For users with time-based indices that
need a different default, this can be managed with index templates. For
users with non-time-based indices that find they need to re-shard with
the split API in place they no longer need to resort only to
reindexing.
Since this has the impact of changing the default number of shards used
in REST tests, we want to ensure that we still have coverage for issues
that could arise from multiple shards. As such, we randomize (rarely)
the default number of shards in REST tests to two. This is managed via a
global index template. However, some tests check the templates that are
in the cluster state during the test. Since this template is randomly
there, we need a way for tests to skip adding the template used to set
the number of shards to two. For this we add the default_shards feature
skip. To avoid having to write our docs in a complicated way because
sometimes they might be behind one shard, and sometimes they might be
behind two shards we apply the default_shards feature skip to all docs
tests. That is, these tests will always run with the default number of
shards (one).
The High Level REST Client's documentation suggested that users should
use the Low Level REST Client for index management activities. This
change removes that suggestion because the high level REST client
supports those APIs now.
This also changes the examples in the migration docs to that still use
the Low Level REST Client to use the non-deprecated varieats of
`performRequest`.
Previously `BulkProcessor` retry logic was based on the exception type of the failed response (`EsRejectedExecutionException`). This commit changes it to be based on the returned status code. This allows us to reproduce the same retry behaviour when the `BulkProcessor` is used from the high-level REST client, which was previously not the case as we cannot rebuild the same exception type when parsing back the response. This change has no effect on the transport client.
Closes#28885
This commit adds the Snapshot Client with a first API call within it,
the get repositories call in snapshot/restore module. This also creates
a snapshot namespace for the docs, as well as get repositories docs.
Relates #27205
This PR adds support for the Get Settings API to the java high-level rest client.
Furthermore, logic related to the retrieval of default settings has been moved from the rest layer into the transport layer and now default settings may be retrieved consistency via both the rest API and the transport API.
Adds two new methods to `RestClient` that take a `Request` object. These
methods will allows us to add more per-request customizable options
without creating more and more and more overloads of the `performRequest`
and `performRequestAsync` methods. These new methods look like:
```
Response performRequest(Request request)
```
and
```
void performRequestAsync(Request request, ResponseListener responseListener)
```
This change doesn't add any actual features but enables adding things like
per request timeouts and per request node selectors. This change *does*
rework the `HighLevelRestClient` and its tests to use these new `Request`
objects and it does update the docs.
This commit adds the distribution type to the startup scripts so that we
can discern from log output and the main response the type of the
distribution (deb/rpm/tar/zip).
As part of adding support for new API to the high-level REST client,
we added support for the `flat_settings` parameter to some of our
request classes. We added documentation that such flag is only ever
read by the high-level REST client, but the truth is that it doesn't
do anything given that settings are always parsed back into a `Settings`
object, no matter whether they are returned in a flat format or not.
It was a mistake to add support for this flag in the context of the
high-level REST client, hence this commit removes it.
This change validates that the `_search` request does not have trailing
tokens after the main object and fails the request with a parsing exception otherwise.
Closes#28995
Some features have been deprecated since `6.0` like the `_parent` field or the
ability to have multiple types per index. This allows to remove quite some
code, which in-turn will hopefully make it easier to proceed with the removal
of types.
Currently the ranking evaluation API doesn't support many of the
standard parameters of the search API. Some of these make sense, like
adding support for the common indices options parameters, which this
change adds.
When the `BulkProcessor` is used with the high-level REST client, a scheduler is internally created that allows to schedule tasks. Such scheduler is not exposed to users and needs to be closed once the `BulkProcessor` is closed. There are two ways to close the `BulkProcessor` though, one is the ordinary `close` method and the other one is `awaitClose`. The former closes the scheduler while the latter doesn't, leaving threads lingering.
* Remove all dependencies from XContentBuilder
This commit removes all of the non-JDK dependencies from XContentBuilder, with
the exception of `CollectionUtils.ensureNoSelfReferences`. It adds a third
extension point around dealing with time-based fields and formatters to work
around the Joda dependency.
This decoupling allows us to be able to move XContentBuilder to a separate lib
so it can be available for things like the high level rest client.
Relates to #28504
Some source files seem to have the execute bit (a+x) set, which doesn't
really seem to hurt but is a bit odd. This change removes those, making
the permissions similar to other source files in the repository.
Adds docs for `HighLevelRestClient#multiSearch`. Unlike the `multiGet`
docs these are much more sparse because multi-search doesn't support
setting many options on the `MultiSearchRequest` and instead just wraps
a list of `SearchRequest`s.
Closes#28389
Currently we store the indices specified in the request URL together with all
the other ranking evaluation specification in RankEvalSpec. This is not ideal
since e.g. the indices are not rendered to xContent and so cannot be parsed
back. Instead we should keep them in RankEvalRequest.
* Decouple XContentBuilder from BytesReference
This commit removes all mentions of `BytesReference` from `XContentBuilder`.
This is needed so that we can completely decouple the XContent code and move it
into its own dependency.
While this change appears large, it is due to two main changes, moving
`.bytes()` and `.string()` out of XContentBuilder itself into static methods
`BytesReference.bytes` and `Strings.toString` respectively. The rest of the
change is code reacting to these changes (the majority of it in tests).
Relates to #28504
The REST status 503 means "I can not handle the request that you sent
me." However today we respond to a main request with a 503 when there
are certain cluster blocks despite still responding with an actual main
response. This is broken, we should respond with a 200 status. This
commit removes this silliness.
The recent addition of the _cluster/settings API was merged together with another change that added encoding of the different URL parts. That broke the cluster PUT settings API straight-away. This commit fixes this problem. The '/' that's part of the /_cluster/settings endpoint should not be encoded.
The REST high-level client supports now encoding of path parts, so that for instance documents with valid ids, but containing characters that need to be encoded as part of urls (`#` etc.), are properly supported. We also make sure that each path part can contain `/` by encoding them properly too.
Closes#28625
* Move to non-deprecated XContentHelper.createParser(...)
This moves away from one of the now-deprecated XContentHelper.createParser
methods in favor of specifying the deprecation logger at parser creation time.
Relates to #28449
Note that this doesn't move all the `createParser` calls because some of them
use the already-deprecated method that doesn't specify the XContentType.
* Remove the deprecated (and now non-needed) createParser method
* [DOCS] expand examples on providing mappings for create index and put mapping
The create index API and put mappings API docs the for high-level Java REST client didn't have a lot of info on how to provide mappings. This commit adds some examples.
This commit splits the async execution documentation into 2 parts, one
for the async method itself and one for the action listener. This allows
to add more doc and to use CountDownLatches in doc tests to wait for
asynchronous operations to be completed before moving to the next test.
It also renames few files.
Related to #28457
Similarly to other documentation tests in the high level client, the
asynchronous operation like update, index or delete can make the test
fail if it sneak in between the middle of another operation.
This commit moves the async doc tests to be the last ones executed and
adds assert busy loops to ensure that the asynchronous operations are
correctly terminated.
closes#28446
Adds allow_partial_search_results flag to search requests with default setting = true.
When false, will error if search either timeouts, has partial errors or has missing shards rather
than returning partial search results. A cluster-level setting provides a default for search requests with no flag.
Closes#27435
This change adds support for the new ranking evaluation API to the High Level Rest Client.
This mostly means adding support for parsing the various response objects back from the
REST representation. It includes one change to the response syntax where previously we didn't
print the type of the metric details section but we now need it to pick the right parser to
parse this section back.
Closes#28198
Script fields can get a bit more complicated than just stored fields. A script can return null, an object and also an array. Extended parsing to support such valid values. Also renamed util method from `parseStoredFieldsValue` to `parseFieldsValue` given that it can parse stored fields but also script fields, anything that's returned as `fields`.
Closes#28380
It has been pointed out that GET with body may cause problems to some proxies. We are then switching to POST the API that retrieve info and support a request body.
Closes#28326
The search request body can never be null as `SearchRequest` doesn't allow the inner `SearchSourceBuilder` to be null. Instead, when search source is not set, the request body is going to be an empty json object (`{}``)
Today, the way to call them API under the indices namespace is by doing e.g. `client.indices().createIndex()`. Our spec define the API under the indices namespace as e.g. `indices.create`, hence there is no need to repeat the index suffix for each method as that is already defined by the namespace. Using the `index` suffix in each method was an oversight which must be corrected.
Several responses include the shards_acknowledged flag (indicating whether the
requisite number of shard copies started before the completion of the operation)
and there are two different getters used : isShardsAcknowledged() and isShardsAcked().
This PR deprecates the isShardsAcked() in favour of isShardsAcknowledged() in
CreateIndexResponse, RolloverResponse and CreateIndexClusterStateUpdateResponse.
Closes#27784
The last operation executed in IndicesClientDocumentationIT.testCreate()
is an asynchronous index creation. Because nothing waits for its
completion, on slow machines the index can sometimes be created after
the testCreate() test is finished, and it can fail the following test.
Closes#27754
This was already changed in 6.x as part of the backport of the recently added open and create index API. wait_for_active_shards can be a number but also "all", with this commit we verify that providing "all" works too.
Today we require users to prepare their indices for split operations.
Yet, we can do this automatically when an index is created which would
make the split feature a much more appealing option since it doesn't have
any 3rd party prerequisites anymore.
This change automatically sets the number of routinng shards such that
an index is guaranteed to be able to split once into twice as many shards.
The number of routing shards is scaled towards the default shard limit per index
such that indices with a smaller amount of shards can be split more often than
larger ones. For instance an index with 1 or 2 shards can be split 10x
(until it approaches 1024 shards) while an index created with 128 shards can only
be split 3x by a factor of 2. Please note this is just a default value and users
can still prepare their indices with `index.number_of_routing_shards` for custom
splitting.
NOTE: this change has an impact on the document distribution since we are changing
the hash space. Documents are still uniformly distributed across all shards but since
we are artificually changing the number of buckets in the consistent hashign space
document might be hashed into different shards compared to previous versions.
This is a 7.0 only change.
This change removes the module named aggs-composite and adds the `composite` aggs
as a core aggregation. This allows other plugins to use this new aggregation
and simplifies the integration in the HL rest client.
Today Cross Cluster Search requires at least one node in each remote cluster to be up once the cross cluster search is run. Otherwise the whole search request fails despite some of the data (either local and/or remote) is available. This happens when performing the _search/shards calls to find out which remote shards the query has to be executed on. This scenario is different from shard failures that may happen later on when the query is actually executed, in case e.g. remote shards are missing, which is not going to fail the whole request but rather yield partial results, and the _shards section in the response will indicate that.
This commit introduces a boolean setting per cluster called search.remote.$cluster_alias.skip_if_disconnected, set to false by default, which allows to skip certain clusters if they are down when trying to reach them through a cross cluster search requests. By default all clusters are mandatory.
Scroll requests support such setting too when they are first initiated (first search request with scroll parameter), but subsequent scroll rounds (_search/scroll endpoint) will fail if some of the remote clusters went down meanwhile.
The search API response contains now a new _clusters section, similar to the _shards section, that gets returned whenever one or more clusters were disconnected and got skipped:
"_clusters" : {
"total" : 3,
"successful" : 2,
"skipped" : 1
}
Such section won't be part of the response if no clusters have been skipped.
The per cluster skip_unavailable setting value has also been added to the output of the remote/info API.
Stardardize underscore requirements in parameters across different type of
requests:
_index, _type, _source, _id keep their underscores
params like version and retry_on_conflict will be without underscores
Throw an error if older versions of parameters are used
BulkRequest, MultiGetRequest, TermVectorcRequest, MoreLikeThisQuery
were changed
Closes#26886
* This change adds a module called `aggs-composite` that defines a new aggregation named `composite`.
The `composite` aggregation is a multi-buckets aggregation that creates composite buckets made of multiple sources.
The sources for each bucket can be defined as:
* A `terms` source, values are extracted from a field or a script.
* A `date_histogram` source, values are extracted from a date field and rounded to the provided interval.
This aggregation can be used to retrieve all buckets of a deeply nested aggregation by flattening the nested aggregation in composite buckets.
A composite buckets is composed of one value per source and is built for each document as the combinations of values in the provided sources.
For instance the following aggregation:
````
"test_agg": {
"terms": {
"field": "field1"
},
"aggs": {
"nested_test_agg":
"terms": {
"field": "field2"
}
}
}
````
... which retrieves the top N terms for `field1` and for each top term in `field1` the top N terms for `field2`, can be replaced by a `composite` aggregation in order to retrieve **all** the combinations of `field1`, `field2` in the matching documents:
````
"composite_agg": {
"composite": {
"sources": [
{
"field1": {
"terms": {
"field": "field1"
}
}
},
{
"field2": {
"terms": {
"field": "field2"
}
}
},
}
}
````
The response of the aggregation looks like this:
````
"aggregations": {
"composite_agg": {
"buckets": [
{
"key": {
"field1": "alabama",
"field2": "almanach"
},
"doc_count": 100
},
{
"key": {
"field1": "alabama",
"field2": "calendar"
},
"doc_count": 1
},
{
"key": {
"field1": "arizona",
"field2": "calendar"
},
"doc_count": 1
}
]
}
}
````
By default this aggregation returns 10 buckets sorted in ascending order of the composite key.
Pagination can be achieved by providing `after` values, the values of the composite key to aggregate after.
For instance the following aggregation will aggregate all composite keys that sorts after `arizona, calendar`:
````
"composite_agg": {
"composite": {
"after": {"field1": "alabama", "field2": "calendar"},
"size": 100,
"sources": [
{
"field1": {
"terms": {
"field": "field1"
}
}
},
{
"field2": {
"terms": {
"field": "field2"
}
}
}
}
}
````
This aggregation is optimized for indices that set an index sorting that match the composite source definition.
For instance the aggregation above could run faster on indices that defines an index sorting like this:
````
"settings": {
"index.sort.field": ["field1", "field2"]
}
````
In this case the `composite` aggregation can early terminate on each segment.
This aggregation also accepts multi-valued field but disables early termination for these fields even if index sorting matches the sources definition.
This is mandatory because index sorting picks only one value per document to perform the sort.
This is the first step to supporting WKT (and other future) format(s). The ShapeBuilders are quite messy and can be simplified by decoupling the parse logic from the build logic. This commit refactors the parsing logic into its own package separate from the Shape builders. It also decouples the GeoShapeType into a standalone enumerator that is responsible for validating the parsed data and providing the appropriate builder. This future-proofs the code making it easier to maintain and add new shape types.
Introduce minimal thread scheduler as a base class for `ThreadPool`. Such a class can be used from the `BulkProcessor` to schedule retries and the flush task. This allows to remove the `ThreadPool` dependency from `BulkProcessor`, which requires to provide settings that contain `node.name` and also needed log4j for logging. Instead, it needs now a `Scheduler` that is much lighter and gets automatically created and shut down on close.
Closes#26028
Request class is currently package protected, making it difficult for
the users to extend the RestHighLevelClient and to use its protected
methods to execute requests. This commit makes the Request class public
and changes few methods of RestHighLevelClient to be protected.
It's easy to create a wrong Content-Type header when converting a
XContentType to a Apache HTTP ContentType instance.
This commit the direct usages of ContentType.create() methods in favor of a Request.createContentType(XContentType) method that does the right thing.
Closes#26438
At current, we do not feel there is enough of a reason to shade the low
level rest client. It caused problems with commons logging and IDE's
during the brief time it was used. We did not know exactly how many
users will need this, and decided that leaving shading out until we
gather more information is best. Users can still shade the jar
themselves. For information and feeback, see issue #26366.
Closes#26328
This reverts commit 3a20922046.
This reverts commit 2c271f0f22.
This reverts commit 9d10dbea39.
This reverts commit e816ef89a2.
The parser for the `ip_range` aggregation response is currently missing from the
NamedXContentRegistry in the high level rest client. Also changes the testing
around the expected number of parsers so we at least check that we register all
the parsers that we also test in InternalAggregationTestCase.
By making RestHighLevelClient Closeable, its close method will close the internal low-level REST client instance by default, which simplifies the way most users interact with the high-level client.
Its constructor accepts now a RestClientBuilder, which clarifies that the low-level REST client is internally created and managed.
It is still possible to provide an already built `RestClient` instance, but that can only be done by subclassing `RestHighLevelClient` and calling the protected constructor that accepts a `RestClient`. In such case a consumer has also to be provided, which controls what has to be done when the high-level client gets done.
Closes#26086
This commit removes all external dependencies from the rest client jar
and shades them in an 'org.elasticsearch.client' package within the jar
using shadowJar gradle plugin. All projects that depended on the
existing jar have been converted to using the 'org.elasticsearch.client'
package prefixes to interact with the rest client.
Closes#25208
We currently use fielddata on the `_id` field which is trappy, especially as we
do it implicitly. This changes the `random_score` function to use doc ids when
no seed is provided and to suggest a field when a seed is provided.
For now the change only emits a deprecation warning when no field is supplied
but this should be replaced by a strict check on 7.0.
Closes#25240
This adds a section about how to add aggregations to the SearchSourceBuilder and how
to retrieve them from a SearchRepsonse to the documentation for the high level rest client.
It was brought up that our current client artifacts have generic names like 'rest' that may cause conflicts with other artifacts.
This commit renames:
- rest -> elasticsearch-rest-client
- sniffer -> elasticsearch-rest-client-sniffer
- rest-high-level -> elasticsearch-rest-high-level-client
A couple of small changes are also preparing the high level client for its first release.
Closes#20248
Today if we search across a large amount of shards we hit every shard. Yet, it's quite
common to search across an index pattern for time based indices but filtering will exclude
all results outside a certain time range ie. `now-3d`. While the search can potentially hit
hundreds of shards the majority of the shards might yield 0 results since there is not document
that is within this date range. Kibana for instance does this regularly but used `_field_stats`
to optimize the indexes they need to query. Now with the deprecation of `_field_stats` and it's upcoming removal a single dashboard in kibana can potentially turn into searches hitting hundreds or thousands of shards and that can easily cause search rejections even though the most of the requests are very likely super cheap and only need a query rewriting to early terminate with 0 results.
This change adds a pre-filter phase for searches that can, if the number of shards are higher than a the `pre_filter_shard_size` threshold (defaults to 128 shards), fan out to the shards
and check if the query can potentially match any documents at all. While false positives are possible, a negative response means that no matches are possible. These requests are not subject to rejection and can greatly reduce the number of shards a request needs to hit. The approach here is preferable to the kibana approach with field stats since it correctly handles aliases and uses the correct threadpools to execute these requests. Further it's completely transparent to the user and improves scalability of elasticsearch in general on large clusters.
Requests that execute a stored script will no longer be allowed to specify the lang of the script. This information is stored in the cluster state making only an id necessary to execute against. Putting a stored script will still require a lang.
This change collapses some of the packages for the bucket aggregations into their parent packages. This was done for the following aggregations:
* The variants of the range aggregation (geo_distance, date and ip) were moved into the `o.e.s.a.bucket.range` package
* The `o.e.s.a.bucket.terms.support` package was removed and the classes were moved to `o.e.s.a.bucket.terms`
* The filter aggregation was moved to `o.e.s.a.bucket.filter`
Since this PR is already relatively large with only the above changes subsequent PRs will do similar operations on relevant metric and pipeline aggregations
Relates to #22868
This commit changes the parsing logic of DocWriteResponse, ReplicationResponse
and GetResult so that it skips any unknown additional fields (for forward compatibility
reasons). This affects the IndexResponse, UpdateResponse,DeleteResponse and
GetResponse objects.
This commit adds a NamedXContentProvider interface that can
be implemented by plugins or modules using Java's SPI feature
in order to provide additional NamedXContent parsers to external
applications like the Java High Level Rest Client.
Some response classes in the java api expose both `getTook()` which returns a `TimeValue` and `getTookInMillis` which returns a `long` value. `getTook()` is enough as one can do `getTook().millis()` to obtain the same result as `getTookInMillis()`, which can be removed.
Currently a `delete document` request against a non-existing index actually **creates** this index.
With this change the `delete document` no longer creates the previously non-existing index and throws an `index_not_found` exception instead.
However as discussed in https://github.com/elastic/elasticsearch/pull/15451#issuecomment-165772026, if an external version is explicitly used, the current behavior is preserved and the index is still created and the document is marked for deletion.
Fixes#15425
* Add parent-join module
This change adds a new module named `parent-join`.
The goal of this module is to provide a replacement for the `_parent` field but as a first step this change only moves the `has_child`, `has_parent` queries and the `children` aggregation to this module.
These queries and aggregations are no longer in core but they are deployed by default as a module.
Relates #20257
We've had `QueryDSLDocumentationTests` for a while but it had a very
hopeful comment at the top about how we want to make sure that the
example in the query-dsl docs match up with the test but we never
had anything that made *sure* that they did. This changes that!
Now the examples from the query-dsl docs are all built from the
`QueryDSLDocumentationTests`. All except for the percolator example
because that is hard to do as it stands now.
To make this easier this change moves `QueryDSLDocumentationTests`
from core and into the high level rest client. This is useful for
two reasons:
1. We expect the high level rest client to be able to use the builders.
2. The code that builds that docs doesn't check out all of
Elasticsearch. It only checks out certain directories. Since we're
already including snippets from that directory we don't have to
make any changes to that process.
Closes#24320
The one argument ctor for `Script` creates a script with the
default language but most usages of are for testing and either
don't care about the language or are for use with
`MockScriptEngine`. This replaces most usages of the one argument
ctor on `Script` with calls to `ESTestCase#mockScript` to make
it clear that the tests don't need the default scripting language.
I've also factored out some copy and pasted script generation
code into a single place. I would have had to change that code
to use `mockScript` anyway, so it was easier to perform the
refactor.
Relates to #16314
When indexing a document via the bulk API where IDs can be explicitly
specified, we currently accept an empty ID. This is problematic because
such a document can not be obtained via the get API. Instead, we should
rejected these requets as accepting them could be a dangerous form of
leniency. Additionally, we already have a way of specifying
auto-generated IDs and that is to not explicitly specify an ID so we do
not need a second way. This commit rejects the individual requests where
ID is specified but empty.
Relates #24118
This commit modifies the BulkProcessor to be decoupled from the
client implementation. Instead it just takes a
BiConsumer<BulkRequest, ActionListener<BulkResponse>> that executes
the BulkRequest.
This commit renames the random ASCII helper methods in ESTestCase. This
is because this method ultimately uses the random ASCII methods from
randomized runner, but these methods actually only produce random
strings generated from [a-zA-Z].
Relates #23886
Today the status is lost when parsing back a BulkItemResponse.Failure. This commit changes the BulkItemResponse.Failure parsing method so that it correctly instantiates a failure with the parsed status instead of realying on the parsed ElasticsearchException (that always return an internal server error status).
This commit adds support for an info() method to the High Level Rest
client that returns the cluster information usually obtained by performing a
`GET hostname:9200` request.
NamedXContentRegistry will be used by the high level REST client to parse aggregation responses, and any section whose class type depends on a json key. There are currently on entries in the standard registry, but soon aggs and most likely suggesters will be added. Also it is possible for subclasses to provide additional named xcontent parsers.
This commit enforces the requirement of Content-Type for the REST layer and removes the deprecated methods in transport
requests and their usages.
While doing this, it turns out that there are many places where *Entity classes are used from the apache http client
libraries and many of these usages did not specify the content type. The methods that do not specify a content type
explicitly have been added to forbidden apis to prevent more of these from entering our code base.
Relates #19388
A previous change aligned the handling of the GET document and HEAD
document APIs. This commit aligns the specification for these two APIs
as well, and fixes a failing test.
Relates #23196
This commit adds support for get and exists api to the high level Java Rest Client. It also adds the infrastructure for other methods to be added in the future.
The RestHighLevelClient class takes as as an argument a low level client instance RestClient. The first method added is ping, which returns true if the call to HEAD / went ok and false if an IOException was thrown. Any other exception gets bubbled up.
There are two kinds of tests, a unit test (RestHighLevelClientTests) that verifies the interaction between high level and low level client, and an integration test (MainActionIT) which relies on an externally started es cluster to send requests to.