When using the High Level Rest Client 6.0.0-beta1, we are missing some transitive dependencies for Lucene as Lucene 7 has not been released yet. See the following `pom.xml`:
```xml
<dependency>
<groupId>org.elasticsearch.client</groupId>
<artifactId>elasticsearch-rest-client</artifactId>
<version>6.0.0-beta1</version>
</dependency>
<dependency>
<groupId>org.elasticsearch.client</groupId>
<artifactId>elasticsearch-rest-high-level-client</artifactId>
<version>6.0.0-beta1</version>
</dependency>
```
It gives:
```
[ERROR] Failed to execute goal on project fscrawler: Could not resolve dependencies for project fr.pilato.elasticsearch.crawler:fscrawler:jar:2.4-SNAPSHOT: The following artifacts could not be resolved: org.apache.lucene:lucene-analyzers-common:jar:7.0.0-snapshot-00142c9, org.apache.lucene:lucene-backward-codecs:jar:7.0.0-snapshot-00142c9, org.apache.lucene:lucene-grouping:jar:7.0.0-snapshot-00142c9, org.apache.lucene:lucene-highlighter:jar:7.0.0-snapshot-00142c9, org.apache.lucene:lucene-join:jar:7.0.0-snapshot-00142c9, org.apache.lucene:lucene-memory:jar:7.0.0-snapshot-00142c9, org.apache.lucene:lucene-misc:jar:7.0.0-snapshot-00142c9, org.apache.lucene:lucene-queries:jar:7.0.0-snapshot-00142c9, org.apache.lucene:lucene-queryparser:jar:7.0.0-snapshot-00142c9, org.apache.lucene:lucene-sandbox:jar:7.0.0-snapshot-00142c9, org.apache.lucene:lucene-spatial:jar:7.0.0-snapshot-00142c9, org.apache.lucene:lucene-spatial-extras:jar:7.0.0-snapshot-00142c9, org.apache.lucene:lucene-spatial3d:jar:7.0.0-snapshot-00142c9, org.apache.lucene:lucene-suggest:jar:7.0.0-snapshot-00142c9: Failure to find org.apache.lucene:lucene-analyzers-common:jar:7.0.0-snapshot-00142c9 in https://artifacts.elastic.co/maven/ was cached in the local repository, resolution will not be reattempted until the update interval of elastic-download-service has elapsed or updates are forced -
```
We need to add some temporary documentation on how to add the missing repository to a gradle or maven project:
```xml
<repository>
<id>elastic-lucene-snapshots</id>
<name>Elastic Lucene Snapshots</name>
<url>http://s3.amazonaws.com/download.elasticsearch.org/lucenesnapshots/00142c9</url>
<releases><enabled>true</enabled></releases>
<snapshots><enabled>false</enabled></snapshots>
</repository>
```
This also applies to the transport client.
Closes#26106.