fix: Update Maven wrapper and document its use to fix version resolut…

…ion (#7620)

* Update the wrapper to include confluentinc/maven#1
* Document what the wrapper does, and how to use it on the CLI and in IDEs

Reviewers: Leah Thomas

.mvn/wrapper/maven-wrapper.properties

@@ -1,4 +1,4 @@
 # custmized maven that help avoid download only highest poms from version range
 # https://issues.apache.org/jira/browse/MRESOLVER-164
-distributionUrl=https://confluent-packaging-tools.s3-us-west-2.amazonaws.com/apache-maven-3.6.3.1-bin.zip
+distributionUrl=https://confluent-packaging-tools.s3-us-west-2.amazonaws.com/apache-maven-3.8.1.2-bin.zip
 wrapperUrl=https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar

CONTRIBUTING.md

@@ -7,12 +7,47 @@ If you have any questions about how to contribute, either [create a GH issue](ht
 
 ## Developing KSQL
 
+### About the Apache Maven wrapper
+
+Development versions of KSQL use version ranges for dependencies
+on other Confluent projects, and due to
+[a bug in Apache Maven](https://issues.apache.org/jira/browse/MRESOLVER-164),
+you may find that both Maven and your IDE download hundreds or thousands
+of pom files while resolving dependencies. They get cached, so it will
+be most apparent on fresh forks or switching to branches that you haven't
+used in a while.
+
+Until we are able to get a fix in and released officially, we need to work
+around the bug. We have added a Maven wrapper script and configured
+it to download a patched version of Maven. You can use this wrapper simply by
+substituting `./mvnw` instead of `mvn` for every Maven invocation.
+The patch is experimental, so if it causes you some trouble, you can switch
+back to the official release just by using `mvn` again. Please let us know
+if you do have any trouble with the wrapper.
+
+You can also configure IntelliJ IDEA to use the patched version of Maven.
+First, get the path to the patched Maven home:
+
+```shell
+$ ./mvnw -v
+...
+Maven home: /home/john/.m2/wrapper/dists/apache-maven-3.8.1.2-bin/1npbma9t0n1k5b22fpopvupbmn/apache-maven-3.8.1.2
+...
+```
+
+Then, update your IDEA Maven home in **Settings > Build, Execution, Deployment > Build Tools > Maven**
+and set the value of **Maven home path** to the same directory listed as the "Maven home" above.
+In the above example, it is `/home/john/.m2/wrapper/dists/apache-maven-3.8.1.2-bin/1npbma9t0n1k5b22fpopvupbmn/apache-maven-3.8.1.2`,
+but it may be different on your machine.
+
+There is likely a similar option available for other IDEs.
+
 ### Building and running KSQL locally
 
 To build and run KSQL locally, run the following commands:
 
 ```shell
-$ ./mvnw clean package -DskipTests -DversionFilter
+$ ./mvnw clean package -DskipTests
 $ ./bin/ksql-server-start -daemon config/ksql-server.properties
 $ ./bin/ksql
 ```
@@ -24,6 +59,16 @@ including any errors.
 If you would rather have the KSQL server logs spool to the console, then
 drop the `-daemon` switch, and start the CLI in a second console.
 
+#### Running in an IDE
+
+You can create a run configuration in your IDE for the main class:
+`io.confluent.ksql.rest.server.KsqlServerMain`, using the classpath
+of the `ksqldb-rest-app` module, and specifying the path to a config
+file as the program argument. There is a basic config available in
+`config/ksql-server.properties`.
+
+You may wish to be sure you have already configured your IDE to use
+the Maven wrapper (see "About the Apache Maven wrapper", above).
 
 ### Testing changes locally