Fix generation of repos using -DhostOnJenkinsGitHub=false

[rrjjvv]

Fixes #709

The fix itself was trivial.

I added integration tests specifically for that scenario, but the tests broke with spotbugs errors (for the generated POM). Example (snippet):

[INFO] [ERROR] Failed to execute goal com.diffplug.spotless:spotless-maven-plugin:2.43.0:check (default) on project testArtifact: The following files had format violations:
[INFO] [ERROR]     pom.xml
[INFO] [ERROR]         @@ -15,16 +15,14 @@
[INFO] [ERROR]          ··<packaging>hpi</packaging>
[INFO] [ERROR]          
[INFO] [ERROR]          ··<name>TODO·Plugin</name>
[INFO] [ERROR]         -··
[INFO] [ERROR]         -··
[INFO] [ERROR]         -··
[INFO] [ERROR]         +
[INFO] [ERROR]          ··<properties>
[INFO] [ERROR]          ····<revision>1.0</revision>
[INFO] [ERROR]          ····<changelist>-SNAPSHOT</changelist>
[INFO] [ERROR]          
[INFO] [ERROR]          ····<!--·https://www.jenkins.io/doc/developer/plugin-development/choosing-jenkins-baseline/·-->
[INFO] [ERROR]          ····<jenkins.version>2.414.3</jenkins.version>
[INFO] [ERROR]         -····
[INFO] [ERROR]         +
[INFO] [ERROR]          ····<spotless.check.skip>false</spotless.check.skip>
[INFO] [ERROR]          ··</properties>
[INFO] [ERROR]          
[INFO] [ERROR] Run 'mvn spotless:apply' to fix these violations.

Obviously a plugin not hosted under the Jenkins umbrella would not be subject to these checks, so turning it off (only for -DhostOnJenkinsGitHub=false) might be considered a viable option, but it was not immediately obvious how to do so, so I explored how I could get the check to pass.

That led to my changing of the templates. It appears that white-space handling may be configurable (thus allowing the templates to remain as-is), but changing the template was easier and I hoped more agreeable. (Subjectively, I find it easier on the eyes as well.)

The key seemed to be having the directives at the beginning of the line. That led to

#if ....
  <stuff>
#end
#if ...
  <stuff>
#end
#if ...
  <stuff>
#end

at which point I collapsed them into a single block.

I broke it into three commits to make it easy to:

1. take the fix only, if that's "good enough"
2. accept the additional tests, if you have a way to turn off the spotbugs check (in lieu of the template changes)

Testing done

Executing the same invocation from #709, but with these fixes:

$ mvn -V archetype:generate -DarchetypeGroupId=io.jenkins.archetypes -DarchetypeArtifactId=empty-plugin -DhostOnJenkinsGitHub=false -DgroupId=mygroup -Dpackage=mypackage -DartifactId=myartifact -DinteractiveMode=false -DarchetypeCatalog=local
Apache Maven 3.9.2 (c9616018c7a021c1c39be70fb2843d6f5f9b8a1c)
Maven home: /opt/maven
Java version: 17.0.10, vendor: Private Build, runtime: /usr/lib/jvm/java-17-openjdk-amd64
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "6.5.0-25-generic", arch: "amd64", family: "unix"
[INFO] Scanning for projects...
[INFO] 
[INFO] ------------------< org.apache.maven:standalone-pom >-------------------
[INFO] Building Maven Stub Project (No POM) 1
[INFO] --------------------------------[ pom ]---------------------------------
[INFO] 
[INFO] >>> archetype:3.2.1:generate (default-cli) > generate-sources @ standalone-pom >>>
[INFO] 
[INFO] <<< archetype:3.2.1:generate (default-cli) < generate-sources @ standalone-pom <<<
[INFO] 
[INFO] 
[INFO] --- archetype:3.2.1:generate (default-cli) @ standalone-pom ---
[INFO] Generating project in Batch mode
[INFO] Archetype [io.jenkins.archetypes:empty-plugin:1.25-SNAPSHOT] found in catalog local
[INFO] ----------------------------------------------------------------------------
[INFO] Using following parameters for creating project from Archetype: empty-plugin:1.25-SNAPSHOT
[INFO] ----------------------------------------------------------------------------
[INFO] Parameter: groupId, Value: mygroup
[INFO] Parameter: artifactId, Value: myartifact
[INFO] Parameter: version, Value: 1.0-SNAPSHOT
[INFO] Parameter: package, Value: mypackage
[INFO] Parameter: packageInPathFormat, Value: mypackage
[INFO] Parameter: package, Value: mypackage
[INFO] Parameter: hostOnJenkinsGitHub, Value: false
[INFO] Parameter: groupId, Value: mygroup
[INFO] Parameter: artifactId, Value: myartifact
[INFO] Parameter: version, Value: 1.0-SNAPSHOT
[WARNING] Don't override file /tmp/myartifact/
[INFO] Executing META-INF/archetype-post-generate.groovy post-generation script
Not hosting on Jenkins Github organisation, removing files specific to jenkinsci
[package:mypackage, hostOnJenkinsGitHub:false, groupId:mygroup, artifactId:myartifact, version:1.0-SNAPSHOT]
[INFO] Project created from Archetype in dir: /tmp/myartifact
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  0.838 s
[INFO] Finished at: 2024-03-14T22:23:34-06:00
[INFO] ------------------------------------------------------------------------
[WARNING] 
[WARNING] Plugin validation issues were detected in 2 plugin(s)
[WARNING] 
[WARNING]  * org.apache.maven.plugins:maven-site-plugin:3.12.1
[WARNING]  * org.apache.maven.plugins:maven-archetype-plugin:3.2.1
[WARNING] 
[WARNING] For more or less details, use 'maven.plugin.validation' property with one of the values (case insensitive): [BRIEF, DEFAULT, VERBOSE]
[WARNING]

$ ls -a myartifact/
.  ..  .gitignore  .mvn  pom.xml  README.md  src

$ grep -i github myartifact/pom.xml
<no output>
$

There are no maven failures, no LICENSE.md, no Jenkinsfile, no .github/, and a correctly named .gitignore.

The new integration tests validates the generated repo meets the same quality checks that a GitHub-hosted repo would, whatever that's worth.

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[timja]

seems fine, an easier approach might be to just run spotless:apply over it in the groovy post script