NPE when executing lock

[Postremus]

On a freshly generated quarkus extension.

Execute:
mvn io.mvnpm:locker-maven-plugin:LATEST:lock -e

On the parent module.

I get this error log.

Martin@THEROCK MINGW64 ~/IdeaProjects/quarkus-redoc
$ mvn io.mvnpm:locker-maven-plugin:LATEST:lock -e
[INFO] Error stacktraces are turned on.
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Build Order:
[INFO]
[INFO] Quarkus Redoc - Parent                                      
       [pom]
[INFO] Quarkus Redoc - Runtime                                     
       [jar]
[INFO] Quarkus Redoc - Deployment                                  
       [jar]
[INFO] Quarkus Redoc - Documentation                               
       [jar]
[INFO] Quarkus Redoc - Integration Tests                           
       [jar]
[INFO] 
[INFO] ----------------< io.quarkiverse:quarkus-redoc-parent >-----------------
[INFO] Building Quarkus Redoc - Parent 999-SNAPSHOT                       [1/5]
[INFO]   from pom.xml
[INFO] --------------------------------[ pom ]---------------------------------
[INFO] 
[INFO] --- locker:1.0.0:lock (default-cli) @ quarkus-redoc-parent ---
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary for Quarkus Redoc - Parent 999-SNAPSHOT:    
[INFO]
[INFO] Quarkus Redoc - Parent ............................. FAILURE [  0.077 s]
[INFO] Quarkus Redoc - Runtime ............................ SKIPPED
[INFO] Quarkus Redoc - Deployment ......................... SKIPPED
[INFO] Quarkus Redoc - Documentation ...................... SKIPPED
[INFO] Quarkus Redoc - Integration Tests .................. SKIPPED
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  0.395 s
[INFO] Finished at: 2026-01-04T19:51:22+01:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal io.mvnpm:locker-maven-plugin:1.0.0:l
ock (default-cli) on project quarkus-redoc-parent: Execution defaul
t-cli of goal io.mvnpm:locker-maven-plugin:1.0.0:lock failed: Canno
t invoke "java.io.File.toPath()" because the return value of "org.apache.maven.project.MavenProject.getFile()" is null -> [Help 1]    
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to e
xecute goal io.mvnpm:locker-maven-plugin:1.0.0:lock (default-cli) o
n project quarkus-redoc-parent: Execution default-cli of goal io.mv
npm:locker-maven-plugin:1.0.0:lock failed: Cannot invoke "java.io.F
ile.toPath()" because the return value of "org.apache.maven.project.MavenProject.getFile()" is null
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2 (MojoExecutor.java:333)
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute (MojoExecutor.java:316)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:212)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:174)
    at org.apache.maven.lifecycle.internal.MojoExecutor.access$000 (MojoExecutor.java:75)
    at org.apache.maven.lifecycle.internal.MojoExecutor$1.run (MojoExecutor.java:162)
    at org.apache.maven.plugin.DefaultMojosExecutionStrategy.execute (DefaultMojosExecutionStrategy.java:39)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:159)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:105)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:73)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:53)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:118)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:261)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:173)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:101)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:906)   
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:283)    
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:206)      
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:77)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:568)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:255)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:201)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:361)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:314)
Caused by: org.apache.maven.plugin.PluginExecutionException: Execut
ion default-cli of goal io.mvnpm:locker-maven-plugin:1.0.0:lock fai
led: Cannot invoke "java.io.File.toPath()" because the return value of "org.apache.maven.project.MavenProject.getFile()" is null      
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:133)
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2 (MojoExecutor.java:328)
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute (MojoExecutor.java:316)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:212)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:174)
    at org.apache.maven.lifecycle.internal.MojoExecutor.access$000 (MojoExecutor.java:75)
    at org.apache.maven.lifecycle.internal.MojoExecutor$1.run (MojoExecutor.java:162)
    at org.apache.maven.plugin.DefaultMojosExecutionStrategy.execute (DefaultMojosExecutionStrategy.java:39)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:159)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:105)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:73)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:53)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:118)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:261)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:173)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:101)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:906)   
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:283)    
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:206)      
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:77)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:568)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:255)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:201)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:361)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:314)
Caused by: java.lang.NullPointerException: Cannot invoke "java.io.F
ile.toPath()" because the return value of "org.apache.maven.project.MavenProject.getFile()" is null
    at io.mvnpm.maven.locker.mojos.LockMojo.getRelativeParentPath (LockMojo.java:132)
    at io.mvnpm.maven.locker.mojos.LockMojo.getParentPom (LockMojo.java:123)
    at io.mvnpm.maven.locker.mojos.LockMojo.execute (LockMojo.java:57)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:126)
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2 (MojoExecutor.java:328)
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute (MojoExecutor.java:316)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:212)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:174)
    at org.apache.maven.lifecycle.internal.MojoExecutor.access$000 (MojoExecutor.java:75)
    at org.apache.maven.lifecycle.internal.MojoExecutor$1.run (MojoExecutor.java:162)
    at org.apache.maven.plugin.DefaultMojosExecutionStrategy.execute (DefaultMojosExecutionStrategy.java:39)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:159)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:105)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:73)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:53)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:118)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:568)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:255)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:201)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:361)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:314)
[ERROR]
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginExecutionException

Martin@THEROCK MINGW64 ~/IdeaProjects/quarkus-redoc
$ cd runtime/

Martin@THEROCK MINGW64 ~/IdeaProjects/quarkus-redoc/runtime
$ mvn io.mvnpm:locker-maven-plugin:LATEST:lock
[INFO] Scanning for projects...
[INFO] 
[INFO] --------------------< io.quarkiverse:quarkus-redoc >--------------------
[INFO] Building Quarkus Redoc - Runtime 999-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[WARNING] The POM for org.mvnpm:js-tokens:jar:1.0.2 is missing, no dependency information available
[WARNING] The POM for org.mvnpm:styled-components:jar:6.1.0 is missing, no dependency information available
[WARNING] The POM for org.mvnpm:styled-components:jar:6.1.1 is missing, no dependency information available
Downloading from mvnpm.org: https://repo.mvnpm.org/maven2/org/mvnpm/at/babel/traverse/7.6.0/traverse-7.6.0.pom
Downloaded from mvnpm.org: https://repo.mvnpm.org/maven2/org/mvnpm/at/babel/traverse/7.6.0/traverse-7.6.0.pom (4.2 kB at 3.3 kB/s)
Downloading from central: https://repo.maven.apache.org/maven2/org/mvnpm/at/babel/traverse/7.6.2/traverse-7.6.2.pom   
Downloading from mvnpm.org: https://repo.mvnpm.org/maven2/org/mvnpm/at/babel/traverse/7.6.2/tra

[ia3andy]

I will have a look, but the locker is not meant to be used on the parent project.
The js is for the dev-ui?

[Postremus]

A simple warning would be nice if used on the parent project instead of failing :)

Still figuring things out, the js / html sources from redoc are most likely going to be used for dev-ui as well as for production mode.

[ia3andy]

Yes agreed on the warning :)

Depending on your case, using https://github.com/mvnpm/esbuild-maven-plugin is a good option because at least everything is bundled as part of the build (and deps are isolated as part of the plugin).

[frederikb]

Another use case which is unsupported and will always lead to an NPE regardless of the lock mode are remote parents.

i.e. consider the case of an app using a corporate POM which is pulled from remote:

<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>
    <parent>
        <groupId>com.example.supercorp</groupId>
        <artifactId>supercorp-parent</artifactId>
        <version>42</version>
        <relativePath/>
        <!-- lookup parent from repository -->
    </parent>
    <groupId>org.foo</groupId>
    <artifactId>bar</artifactId>
    <version>999-SNAPSHOT</version>
    <name>Bar</name>

This leads to an NPE regardless of the lock mode because it always attempts to resolve the parent POM, even if that is only needed in case of the LOCKER_BOM mode.

The NPE is thrown because getFile returns null for this case - at least for my setup:

locker/src/main/java/io/mvnpm/maven/locker/mojos/LockMojo.java

Line 132 in e4661c7

final Path parentPath = project.getParent().getFile().toPath().toAbsolutePath();

I haven't debugged it any further and I otherwise lack experience with Maven plugin internals.

I don't see any tests of this scenario so am I correct in my understanding that it is not supported as of now?

[frederikb]

Looking into it some more I ran into an issue with maven-model-helper which currently doesn't correctly handle an empty <relativePath/> ( fabric8io/maven-model-helper#225 ).

[ia3andy]

@frederikb will you fix this issue?

[ia3andy]

and thanks for the care on the project !!

[frederikb]

@ia3andy Sure, I’ll take a stab at it — and you’re very welcome. We’re evaluating it for our use case, so I felt it was only right to give something back and support our use case at the same time.