[Docs] Update Java Low-Level documentation to reflect shaded deps (#25882)

Since #25208 the Java Low-Level Rest Client has shaded dependencies. This commit updates the documentation to reflect that.

docs/java-rest/low-level/configuration.asciidoc

@@ -12,8 +12,8 @@ additional configuration for the low-level Java REST Client.
 
 Configuring requests timeouts can be done by providing an instance of
 `RequestConfigCallback` while building the `RestClient` through its builder.
-The interface has one method that receives an instance of
-https://hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/org/apache/http/client/config/RequestConfig.Builder.html[`org.apache.http.client.config.RequestConfig.Builder`]
+The interface has one method that receives an instance of `org.elasticsearch.client.http.client.config.RequestConfig.Builder`
+(see the https://hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/org/apache/http/client/config/RequestConfig.Builder.html[Apache documentation])
  as an argument and has the same return type. The request config builder can
 be modified and then returned. In the following example we increase the
 connect timeout (defaults to 1 second) and the socket timeout (defaults to 30
@@ -42,8 +42,8 @@ include-tagged::{doc-tests}/RestClientDocumentation.java[rest-client-config-thre
 
 Configuring basic authentication can be done by providing an
 `HttpClientConfigCallback` while building the `RestClient` through its builder.
-The interface has one method that receives an instance of
-https://hc.apache.org/httpcomponents-asyncclient-dev/httpasyncclient/apidocs/org/apache/http/impl/nio/client/HttpAsyncClientBuilder.html[`org.apache.http.impl.nio.client.HttpAsyncClientBuilder`]
+The interface has one method that receives an instance of `org.elasticsearch.client.http.impl.nio.client.HttpAsyncClientBuilder`
+(see the https://hc.apache.org/httpcomponents-asyncclient-dev/httpasyncclient/apidocs/org/apache/http/impl/nio/client/HttpAsyncClientBuilder.html[Apache documentation])
  as an argument and has the same return type. The http client builder can be
 modified and then returned. In the following example we set a default
 credentials provider that requires basic authentication.
@@ -67,8 +67,8 @@ include-tagged::{doc-tests}/RestClientDocumentation.java[rest-client-config-disa
 === Encrypted communication
 
 Encrypted communication can also be configured through the
-`HttpClientConfigCallback`. The
-https://hc.apache.org/httpcomponents-asyncclient-dev/httpasyncclient/apidocs/org/apache/http/impl/nio/client/HttpAsyncClientBuilder.html[`org.apache.http.impl.nio.client.HttpAsyncClientBuilder`]
+`HttpClientConfigCallback`. The `org.elasticsearch.client.http.impl.nio.client.HttpAsyncClientBuilder`
+(see the https://hc.apache.org/httpcomponents-asyncclient-dev/httpasyncclient/apidocs/org/apache/http/impl/nio/client/HttpAsyncClientBuilder.html[Apache documentation])
  received as an argument exposes multiple methods to configure encrypted
  communication: `setSSLContext`, `setSSLSessionStrategy` and
  `setConnectionManager`, in order of precedence from the least important.

docs/java-rest/low-level/index.asciidoc

@@ -6,8 +6,6 @@
 
 The low-level client's features include:
 
-* minimal dependencies
-
 * load balancing across all available nodes
 
 * failover in case of node failures and upon specific response codes
@@ -22,6 +20,8 @@ The low-level client's features include:
 
 * optional automatic <<sniffer,discovery of cluster nodes>>
 
+* packaged as a single JAR file that shades all dependencies
+
 --
 
 :doc-tests: {docdir}/../../client/rest/src/test/java/org/elasticsearch/client/documentation

docs/java-rest/low-level/usage.asciidoc

@@ -48,10 +48,7 @@ dependencies {
 [[java-rest-low-usage-dependencies]]
 === Dependencies
 
-The low-level Java REST client internally uses the
-http://hc.apache.org/httpcomponents-asyncclient-dev/[Apache Http Async Client]
- to send http requests. It depends on the following artifacts, namely the async
- http client and its own transitive dependencies:
+The low-level Java REST client uses several https://www.apache.org/[Apache] libraries:
 
 - org.apache.httpcomponents:httpasyncclient
 - org.apache.httpcomponents:httpcore-nio
@@ -61,6 +58,13 @@ http://hc.apache.org/httpcomponents-asyncclient-dev/[Apache Http Async Client]
 - commons-logging:commons-logging
 
 
+One of the most important is the http://hc.apache.org/httpcomponents-asyncclient-dev/[Apache Http Async Client]
+ which is used to send http requests. In order to avoid version conflicts, these dependencies are shaded and
+ packaged within the client in a single JAR file (sometimes called "uber jar" or "fat jar"). Shading a dependency
+ consists of taking its content (resources files and Java class files), rename its packages (all package names
+ that start with `org.apache` are renamed to `org.elasticsearch.client`) before putting them in the same JAR file
+as the low-level Java REST client.
+
 [[java-rest-low-usage-initialization]]
 === Initialization
 
@@ -117,18 +121,16 @@ need to be taken. Used internally when sniffing on failure is enabled.
 include-tagged::{doc-tests}/RestClientDocumentation.java[rest-client-init-request-config-callback]
 --------------------------------------------------
 <1> Set a callback that allows to modify the default request configuration
-(e.g. request timeouts, authentication, or anything that the
-https://hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/org/apache/http/client/config/RequestConfig.Builder.html[`org.apache.http.client.config.RequestConfig.Builder`]
- allows to set)
+(e.g. request timeouts, authentication, or anything that the `org.elasticsearch.client.http.client.config.RequestConfig.Builder`
+allows to set). For more information, see the https://hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/org/apache/http/client/config/RequestConfig.Builder.html[Apache documentation]
 
 ["source","java",subs="attributes,callouts,macros"]
 --------------------------------------------------
 include-tagged::{doc-tests}/RestClientDocumentation.java[rest-client-init-client-config-callback]
 --------------------------------------------------
 <1> Set a callback that allows to modify the http client configuration
-(e.g. encrypted communication over ssl, or anything that the
-http://hc.apache.org/httpcomponents-asyncclient-dev/httpasyncclient/apidocs/org/apache/http/impl/nio/client/HttpAsyncClientBuilder.html[`org.apache.http.impl.nio.client.HttpAsyncClientBuilder`]
- allows to set)
+(e.g. encrypted communication over ssl, or anything that the `org.elasticsearch.client.http.impl.nio.client.HttpAsyncClientBuilder`
+ allows to set). For more information, see the http://hc.apache.org/httpcomponents-asyncclient-dev/httpasyncclient/apidocs/org/apache/http/impl/nio/client/HttpAsyncClientBuilder.html[Apache documentation]
 
 
 [[java-rest-low-usage-requests]]
@@ -162,7 +164,7 @@ parameter
 include-tagged::{doc-tests}/RestClientDocumentation.java[rest-client-verb-endpoint-params-body]
 --------------------------------------------------
 <1> Send a request by providing the verb, the endpoint, optional querystring
-parameters and the request body enclosed in an `org.apache.http.HttpEntity`
+parameters and the request body enclosed in an `org.elasticsearch.client.http.HttpEntity`
 object
 
 IMPORTANT: The `ContentType` specified for the `HttpEntity` is important
@@ -175,7 +177,7 @@ include-tagged::{doc-tests}/RestClientDocumentation.java[rest-client-response-co
 --------------------------------------------------
 <1> Send a request by providing the verb, the endpoint, optional querystring
 parameters, optional request body and the optional factory that is used to
-create an http://hc.apache.org/httpcomponents-core-ga/httpcore-nio/apidocs/org/apache/http/nio/protocol/HttpAsyncResponseConsumer.html[`org.apache.http.nio.protocol.HttpAsyncResponseConsumer`]
+create a `org.elasticsearch.client.http.nio.protocol.HttpAsyncResponseConsumer` (see the http://hc.apache.org/httpcomponents-core-ga/httpcore-nio/apidocs/org/apache/http/nio/protocol/HttpAsyncResponseConsumer.html[Apache documentation])
 callback instance per request attempt. Controls how the response body gets
 streamed from a non-blocking HTTP connection on the client side. When not
 provided, the default implementation is used which buffers the whole response
@@ -205,7 +207,7 @@ include-tagged::{doc-tests}/RestClientDocumentation.java[rest-client-verb-endpoi
 --------------------------------------------------
 <1> Send an async request by providing the verb, the endpoint, optional
 querystring parameters, the request body enclosed in an
-`org.apache.http.HttpEntity` object and the response listener to be
+`org.elasticsearch.client.http.HttpEntity` object and the response listener to be
 notified once the request is completed
 
 ["source","java",subs="attributes,callouts,macros"]
@@ -214,7 +216,7 @@ include-tagged::{doc-tests}/RestClientDocumentation.java[rest-client-response-co
 --------------------------------------------------
 <1> Send an async request by providing the verb, the endpoint, optional
 querystring parameters, optional request body and the optional factory that is
-used to create an http://hc.apache.org/httpcomponents-core-ga/httpcore-nio/apidocs/org/apache/http/nio/protocol/HttpAsyncResponseConsumer.html[`org.apache.http.nio.protocol.HttpAsyncResponseConsumer`]
+used to create a `org.elasticsearch.client.http.nio.protocol.HttpAsyncResponseConsumer` (see the http://hc.apache.org/httpcomponents-core-ga/httpcore-nio/apidocs/org/apache/http/nio/protocol/HttpAsyncResponseConsumer.html[Apache documentation])
 callback instance per request attempt. Controls how the response body gets
 streamed from a non-blocking HTTP connection on the client side. When not
 provided, the default implementation is used which buffers the whole response
@@ -258,8 +260,8 @@ include-tagged::{doc-tests}/RestClientDocumentation.java[rest-client-response2]
 <2> The host that returned the response
 <3> The response status line, from which you can for instance retrieve the status code
 <4> The response headers, which can also be retrieved by name though `getHeader(String)`
-<5> The response body enclosed in an https://hc.apache.org/httpcomponents-core-ga/httpcore/apidocs/org/apache/http/HttpEntity.html[`org.apache.http.HttpEntity`]
- object
+<5> The response body enclosed in a `org.elasticsearch.client.http.HttpEntity` object
+(see the https://hc.apache.org/httpcomponents-core-ga/httpcore/apidocs/org/apache/http/HttpEntity.html[Apache documentation]
 
 When performing a request, an exception is thrown (or received as an argument
  in `ResponseListener#onFailure(Exception)` in the following scenarios:
@@ -286,14 +288,12 @@ Note that the low-level client doesn't expose any helper for json marshalling
 and un-marshalling. Users are free to use the library that they prefer for that
 purpose.
 
-The underlying Apache Async Http Client ships with different
-https://hc.apache.org/httpcomponents-core-ga/httpcore/apidocs/org/apache/http/HttpEntity.html[`org.apache.http.HttpEntity`]
+The low-level Java Rest Client ships with different `org.elasticsearch.client.http.HttpEntity`
  implementations that allow to provide the request body in different formats
 (stream, byte array, string etc.). As for reading the response body, the
 `HttpEntity#getContent` method comes handy which returns an `InputStream`
 reading from the previously buffered response body. As an alternative, it is
-possible to provide a custom
-http://hc.apache.org/httpcomponents-core-ga/httpcore-nio/apidocs/org/apache/http/nio/protocol/HttpAsyncResponseConsumer.html[`org.apache.http.nio.protocol.HttpAsyncResponseConsumer`]
+possible to provide a custom org.elasticsearch.client.http.nio.protocol.HttpAsyncResponseConsumer`
  that controls how bytes are read and buffered.
 
 [[java-rest-low-usage-logging]]