hadoop-hdds/hadoop-dependency-client/README.md

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This helper project provides a reduced view to the Hadoop dependencies. Hadoop common by default depends on a lot of other projects
which are not required for the parts used in Ozone.

The exclude rules should be updated on each version bump. If Hadoop introduce new dependencies we need to exclude them (unless they are required).


For the reference here are the minimal jar files which are required by Ozone:


```
mvn dependency:tree 

[INFO] Scanning for projects...
[INFO] 
[INFO] -------< org.apache.hadoop:hadoop-hdds-hadoop-dependency-client >-------
[INFO] Building Apache Hadoop HDDS Hadoop Client dependencies 1.0.0
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- maven-dependency-plugin:3.0.2:tree (default-cli) @ hadoop-hdds-hadoop-dependency-client ---
[INFO] org.apache.hadoop:hadoop-hdds-hadoop-dependency-client:jar:1.0.0
[INFO] +- org.apache.hadoop:hadoop-annotations:jar:3.2.1:compile
[INFO] |  \- jdk.tools:jdk.tools:jar:1.8:system
[INFO] +- org.apache.hadoop:hadoop-common:jar:3.2.1:compile
[INFO] |  +- org.apache.httpcomponents:httpclient:jar:4.5.2:compile
[INFO] |  |  \- org.apache.httpcomponents:httpcore:jar:4.4.4:compile
[INFO] |  +- org.apache.commons:commons-configuration2:jar:2.1.1:compile
[INFO] |  +- com.google.re2j:re2j:jar:1.1:compile
[INFO] |  +- com.google.protobuf:protobuf-java:jar:2.5.0:compile
[INFO] |  +- org.apache.hadoop:hadoop-auth:jar:3.2.1:compile
[INFO] |  +- com.google.code.findbugs:jsr305:jar:3.0.0:compile
[INFO] |  +- org.apache.htrace:htrace-core4:jar:4.1.0-incubating:compile
[INFO] |  +- org.codehaus.woodstox:stax2-api:jar:3.1.4:compile
[INFO] |  \- com.fasterxml.woodstox:woodstox-core:jar:5.0.3:compile
[INFO] +- org.apache.hadoop:hadoop-hdfs:jar:3.2.1:compile
[INFO] \- junit:junit:jar:4.11:test
[INFO]    \- org.hamcrest:hamcrest-core:jar:1.3:test
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.464 s
[INFO] Finished at: 2020-08-25T19:40:29+08:00
[INFO] ------------------------------------------------------------------------
```