Csdrhrt

I developed my own (very simple) custom Maven plugin following this guide.

All it does is execute my own project's Main class after running a specific goal.

When I run mvn install on my plugin, I get a NullPointerException on the maven-plugin-plugin:descriptor goal. It is important to mention that this doesn't happen if I add the dependency with a <systemPath> absolute path, adding the <scope>system</scope> option.

Stack trace:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-plugin-plugin:3.2:descriptor (default-descriptor) on project gentest-maven-plugin: Execution default-descriptor of goal org.apache.maven.plugins:maven-plugin-plugin:3.2:descriptor failed.: NullPointerException -> [Help 1]

org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-plugin-plugin:3.2:descriptor (default-descriptor) on project gentest-maven-plugin: Execution default-descriptor of goal org.apache.maven.plugins:maven-plugin-plugin:3.2:descriptor failed.

    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:213)

    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:154)

    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:146)

    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:51)

    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)

    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:309)

    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:194)

    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:107)

    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:955)

    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:290)

    at org.apache.maven.cli.MavenCli.main (MavenCli.java:194)

    at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)

    at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)

    at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)

    at java.lang.reflect.Method.invoke (Method.java:498)

    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:289)

    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:229)

    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:415)

    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:356)

Caused by: org.apache.maven.plugin.PluginExecutionException: Execution default-descriptor of goal org.apache.maven.plugins:maven-plugin-plugin:3.2:descriptor failed.

    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:145)

    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:208)

    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:154)

    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:146)

    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:51)

    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)

    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:309)

    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:194)

    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:107)

    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:955)

    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:290)

    at org.apache.maven.cli.MavenCli.main (MavenCli.java:194)

    at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)

    at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)

    at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)

    at java.lang.reflect.Method.invoke (Method.java:498)

    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:289)

    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:229)

    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:415)

    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:356)

Caused by: java.lang.NullPointerException

    at org.objectweb.asm.Type.getObjectType (Unknown Source)

    at org.apache.maven.tools.plugin.annotations.scanner.visitors.MojoClassVisitor.visit (MojoClassVisitor.java:108)

    at org.objectweb.asm.ClassReader.accept (Unknown Source)

    at org.objectweb.asm.ClassReader.accept (Unknown Source)

    at org.apache.maven.tools.plugin.annotations.scanner.DefaultMojoAnnotationsScanner.scanFile (DefaultMojoAnnotationsScanner.java:139)

    at org.apache.maven.tools.plugin.annotations.scanner.DefaultMojoAnnotationsScanner.scan (DefaultMojoAnnotationsScanner.java:85)

    at org.apache.maven.tools.plugin.annotations.JavaAnnotationsMojoDescriptorExtractor.scanAnnotations (JavaAnnotationsMojoDescriptorExtractor.java:125)

    at org.apache.maven.tools.plugin.annotations.JavaAnnotationsMojoDescriptorExtractor.execute (JavaAnnotationsMojoDescriptorExtractor.java:104)

    at org.apache.maven.tools.plugin.scanner.DefaultMojoScanner.populatePluginDescriptor (DefaultMojoScanner.java:108)

    at org.apache.maven.plugin.plugin.AbstractGeneratorMojo.execute (AbstractGeneratorMojo.java:233)

    at org.apache.maven.plugin.plugin.DescriptorGeneratorMojo.execute (DescriptorGeneratorMojo.java:92)

    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:134)

    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:208)

    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:154)

    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:146)

    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:51)

    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)

    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:309)

    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:194)

    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:107)

    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:955)

    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:290)

    at org.apache.maven.cli.MavenCli.main (MavenCli.java:194)

    at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)

    at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)

    at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)

    at java.lang.reflect.Method.invoke (Method.java:498)

    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:289)

    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:229)

    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:415)

    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:356)

My plugin's pom.xml:

<?xml version="1.0" encoding="UTF-8"?>

<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>



    <groupId>com.example</groupId>

    <artifactId>example-maven-plugin</artifactId>

    <version>1.0-SNAPSHOT</version>

    <packaging>maven-plugin</packaging>



    <build>

        <plugins>

            <plugin>

                <groupId>com.example</groupId>

                <artifactId>example-maven-plugin</artifactId>

                <version>1.0-SNAPSHOT</version>

            </plugin>

            <plugin>

                <groupId>org.apache.maven.plugins</groupId>

                <artifactId>maven-compiler-plugin</artifactId>

                <configuration>

                    <source>8</source>

                    <target>8</target>

                </configuration>

            </plugin>

        </plugins>

    </build>



    <dependencies>

        <dependency>

            <groupId>org.apache.maven</groupId>

            <artifactId>maven-plugin-api</artifactId>

            <version>3.0</version>

        </dependency>

        <dependency>

            <groupId>org.apache.maven.plugin-tools</groupId>

            <artifactId>maven-plugin-annotations</artifactId>

            <version>3.4</version>

            <scope>provided</scope>

        </dependency>

        <dependency>

            <groupId>com.example</groupId>

            <artifactId>myexample</artifactId>

            <version>1.0-SNAPSHOT</version>

        </dependency>

    </dependencies>

</project>

What I've tried is manually installing my project with mvn install:install-file following this small guide.

Solved. Added the following snippet to my pom.xml (won't work with 3.4 version).

    <plugin>

        <groupId>org.apache.maven.plugins</groupId>

        <artifactId>maven-plugin-plugin</artifactId>

        <version>3.5</version>

    </plugin>