"InstantiationException: java.util.List" with Maven 2

[ebourg]

Hi,

I got the following error when running depgraph on a project with Maven 2:

[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Failed to configure plugin parameters for: com.github.ferstl:depgraph-maven-plugin:1.0.1

Cause: Class 'java.util.List' cannot be instantiated
[INFO] ------------------------------------------------------------------------
[DEBUG] Trace
org.apache.maven.lifecycle.LifecycleExecutionException: Error configuring: com.github.ferstl:depgraph-maven-plugin. Reason: Unable to p
arse the created DOM for plugin configuration
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:723)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeStandaloneGoal(DefaultLifecycleExecutor.java:569)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:539)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:387)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:284)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:180)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:328)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138)
        at org.apache.maven.cli.MavenCli.main(MavenCli.java:362)
        at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:60)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
        at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
        at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
        at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
Caused by: org.apache.maven.plugin.PluginConfigurationException: Error configuring: com.github.ferstl:depgraph-maven-plugin. Reason: Unable to parse the created DOM for plugin configuration
        at org.apache.maven.plugin.DefaultPluginManager.populatePluginFields(DefaultPluginManager.java:1363)
        at org.apache.maven.plugin.DefaultPluginManager.getConfiguredMojo(DefaultPluginManager.java:724)
        at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:468)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:694)
        ... 17 more
Caused by: org.codehaus.plexus.component.configurator.ComponentConfigurationException: Class 'java.util.List' cannot be instantiated
        at org.codehaus.plexus.component.configurator.converters.AbstractConfigurationConverter.instantiateObject(AbstractConfigurationConverter.java:121)
        at org.codehaus.plexus.component.configurator.converters.composite.CollectionConverter.fromConfiguration(CollectionConverter.java:73)
        at org.codehaus.plexus.component.configurator.converters.ComponentValueSetter.configure(ComponentValueSetter.java:247)
        at org.codehaus.plexus.component.configurator.converters.composite.ObjectWithFieldsConverter.processConfiguration(ObjectWithFieldsConverter.java:137)
        at org.codehaus.plexus.component.configurator.BasicComponentConfigurator.configureComponent(BasicComponentConfigurator.java:56)
        at org.apache.maven.plugin.DefaultPluginManager.populatePluginFields(DefaultPluginManager.java:1357)
        ... 20 more
Caused by: java.lang.InstantiationException: java.util.List
        at java.lang.Class.newInstance(Class.java:359)
        at org.codehaus.plexus.component.configurator.converters.AbstractConfigurationConverter.instantiateObject(AbstractConfigurationConverter.java:111)
        ... 25 more

It didn't happen with Maven 3. If this issue can't be resolved I guess the plugin should have a prereq on Maven 3.

[ferstl]

Hi, you are right. I tried several maven versions from 2.2.1 (the last Maven 2 version) up to 3.2.5 (the most recent one). It turned out that 3.0.4 is the first version on which this plugin works. I'll change the <prerequisites> accordingly.