Mirror mojo does not seem to work for target platforms

[rcspirent]

Trying to use tycho-p2-extras-plugin:mirror mojo to mirror a targetplatform which should be possible according to https://www.eclipse.org/tycho/sitedocs/tycho-extras/tycho-p2-extras-plugin/mirror-mojo.html#targetPlatformAsSource but I couldn't find an example or further info anywhere.
So I tried around but couldn't figure it out.

Example pom

<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>example.p2mirror</groupId>
	<artifactId>targetplatform.mirror</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>eclipse-repository</packaging>
	<name>targetplatform mirror</name>

	<properties>
		<tycho-version>2.3.0</tycho-version>
	</properties>

	<build>
		<plugins>
			<plugin>
				<groupId>org.eclipse.tycho</groupId>
				<artifactId>tycho-maven-plugin</artifactId>
				<version>${tycho-version}</version>
				<extensions>true</extensions>
			</plugin>
			<plugin>
				<groupId>org.eclipse.tycho.extras</groupId>
				<artifactId>tycho-p2-extras-plugin</artifactId>
				<version>${tycho-version}</version>
				<executions>
					<execution>
						<phase>prepare-package</phase>
						<goals>
							<goal>mirror</goal>
						</goals>
					</execution>
				</executions>
				<configuration>
					<ignoreErrors>false</ignoreErrors>
					<includeOptional>true</includeOptional>
					<includeNonGreedy>false</includeNonGreedy>
					<filter>
					</filter>
					<latestVersionOnly>true</latestVersionOnly>
					<mirrorMetadataOnly>false</mirrorMetadataOnly>
					<compress>false</compress>
					<append>false</append>
					<includePacked>true</includePacked>
					<targetPlatformAsSource>true</targetPlatformAsSource>
					<currentModuleAsSource>false</currentModuleAsSource>
					<source>
					</source>
				</configuration>
			</plugin>
			<plugin>
				<groupId>org.eclipse.tycho</groupId>
				<artifactId>tycho-p2-plugin</artifactId>
				<version>${tycho-version}</version>
			</plugin>
			<plugin>
				<groupId>org.eclipse.tycho</groupId>
				<artifactId>target-platform-configuration</artifactId>
				<version>${tycho-version}</version>
				<configuration>
					<allowConflictingDependencies>true</allowConflictingDependencies>
					<target>
						<file>custom.target</file>
					</target>
				</configuration>
			</plugin>
		</plugins>
	</build>
</project>

Execution via mvn package results in a mostly empty p2 repository.
Direct mojo execution results in

[ERROR] Failed to execute goal org.eclipse.tycho.extras:tycho-p2-extras-plugin:2.3.0:mirror (default-cli) on project targetplatform.mirror: Execution default-cli of goal org.eclipse.tycho.extras:tycho-p2-extras-plugin:2.3.0:mirror failed: Tycho build extension not configured for MavenProject: example.p2mirror:targetplatform.mirror:0.0.1-SNAPSHOT @ C:\dev\eclipse_ws\targetplatform.mirror\pom.xml -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.eclipse.tycho.extras:tycho-p2-extras-plugin:2.3.0:mirror (default-cli) on project targetplatform.mirror: Execution default-cli of goal org.eclipse.tycho.extras:tycho-p2-extras-plugin:2.3.0:mirror failed: Tycho build extension not configured for MavenProject: example.p2mirror:targetplatform.mirror:0.0.1-SNAPSHOT @ C:\dev\eclipse_ws\targetplatform.mirror\pom.xml
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:215)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:156)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:148)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:117)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:81)
	at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:56)
	at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:305)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:192)
	at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:105)
	at org.apache.maven.cli.MavenCli.execute(MavenCli.java:957)
	at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:289)
	at org.apache.maven.cli.MavenCli.main(MavenCli.java:193)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:282)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:225)
	at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:406)
	at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:347)
Caused by: org.apache.maven.plugin.PluginExecutionException: Execution default-cli of goal org.eclipse.tycho.extras:tycho-p2-extras-plugin:2.3.0:mirror failed: Tycho build extension not configured for MavenProject: example.p2mirror:targetplatform.mirror:0.0.1-SNAPSHOT @ C:\dev\eclipse_ws\targetplatform.mirror\pom.xml
	at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:148)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:210)
	... 20 more
Caused by: java.lang.IllegalStateException: Tycho build extension not configured for MavenProject: example.p2mirror:targetplatform.mirror:0.0.1-SNAPSHOT @ C:\dev\eclipse_ws\targetplatform.mirror\pom.xml
	at org.eclipse.tycho.core.utils.TychoProjectUtils.getTargetPlatform(TychoProjectUtils.java:70)
	at org.eclipse.tycho.p2.facade.RepositoryReferenceTool.addTargetPlatformRepository(RepositoryReferenceTool.java:118)
	at org.eclipse.tycho.p2.facade.RepositoryReferenceTool.getVisibleRepositories(RepositoryReferenceTool.java:98)
	at org.eclipse.tycho.plugins.p2.extras.MirrorMojo.execute(MirrorMojo.java:234)
	at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:137)
	... 21 more

[LorenzoBettini]

I was trying to figure out how to use that option. Any suggestions, please?

[laeubi]

I was trying to figure out how to use that option. Any suggestions, please?

The best option is to create a small (github) project showing the error then we can discuss/improve on it.

[LorenzoBettini]

@laeubi I didn't experience any error: I simply have no idea on how to use that option..