[MPH-222] Maven help evaluate problems

**[Tamas Cservenak](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=cstamas)** opened **[MPH-222](https://issues.apache.org/jira/browse/MPH-222?redirect=false)** and commented

If you invoke with mvn master

```
$ mvn help:evaluate -Dexpression=project.repositories
```

or

```
$ mvn help:evaluate -Dexpression=settings.repositories
```

it explodes with:

```
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-help-plugin:3.4.1:evaluate (default-cli) on project maven: Execution default-cli of goal org.apache.maven.plugins:maven-help-plugin:3.4.1:evaluate failed: No converter available
[ERROR] ---- Debugging information ----
[ERROR] message : No converter available
[ERROR] type : org.apache.maven.model.WrapperList
[ERROR] converter : com.thoughtworks.xstream.converters.reflection.ReflectionConverter
[ERROR] message[1] : Unable to make field protected transient int java.util.AbstractList.modCount accessible: module java.base does not "opens java.util" to unnamed module @33fec21
[ERROR] -------------------------------
[ERROR] -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-help-plugin:3.4.1:evaluate (default-cli) on project maven: Execution default-cli of goal org.apache.maven.plugins:maven-help-plugin:3.4.1:evaluate failed: No converter available
---- Debugging information ----
message : No converter available
type : org.apache.maven.model.WrapperList
converter : com.thoughtworks.xstream.converters.reflection.ReflectionConverter
message[1] : Unable to make field protected transient int java.util.AbstractList.modCount accessible: module java.base does not "opens java.util" to unnamed module @33fec21
-------------------------------
at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2(MojoExecutor.java:346)
at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute(MojoExecutor.java:310)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:214)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:179)
at org.apache.maven.lifecycle.internal.MojoExecutor$1.run(MojoExecutor.java:168)
at org.apache.maven.plugin.DefaultMojosExecutionStrategy.execute(DefaultMojosExecutionStrategy.java:39)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:165)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:110)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:76)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:60)
at org.apache.maven.lifecycle.internal.DefaultLifecycleStarter.execute(DefaultLifecycleStarter.java:123)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:311)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:225)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:149)
at org.apache.maven.cling.invoker.mvn.MavenInvoker.doExecute(MavenInvoker.java:454)
at org.apache.maven.cling.invoker.mvn.MavenInvoker.execute(MavenInvoker.java:97)
at org.apache.maven.cling.invoker.mvn.MavenInvoker.execute(MavenInvoker.java:78)
at org.apache.maven.cling.invoker.LookupInvoker.doInvoke(LookupInvoker.java:166)
at org.apache.maven.cling.invoker.LookupInvoker.invoke(LookupInvoker.java:132)
at org.apache.maven.cling.ClingSupport.run(ClingSupport.java:64)
at org.apache.maven.cling.MavenCling.main(MavenCling.java:49)
at jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
at java.lang.reflect.Method.invoke(Method.java:580)
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: Execution default-cli of goal org.apache.maven.plugins:maven-help-plugin:3.4.1:evaluate failed: No converter available
---- Debugging information ----
message : No converter available
type : org.apache.maven.model.WrapperList
converter : com.thoughtworks.xstream.converters.reflection.ReflectionConverter
message[1] : Unable to make field protected transient int java.util.AbstractList.modCount accessible: module java.base does not "opens java.util" to unnamed module @33fec21
-------------------------------
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:152)
at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2(MojoExecutor.java:339)
at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute(MojoExecutor.java:310)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:214)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:179)
at org.apache.maven.lifecycle.internal.MojoExecutor$1.run(MojoExecutor.java:168)
at org.apache.maven.plugin.DefaultMojosExecutionStrategy.execute(DefaultMojosExecutionStrategy.java:39)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:165)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:110)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:76)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:60)
at org.apache.maven.lifecycle.internal.DefaultLifecycleStarter.execute(DefaultLifecycleStarter.java:123)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:311)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:225)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:149)
at org.apache.maven.cling.invoker.mvn.MavenInvoker.doExecute(MavenInvoker.java:454)
at org.apache.maven.cling.invoker.mvn.MavenInvoker.execute(MavenInvoker.java:97)
at org.apache.maven.cling.invoker.mvn.MavenInvoker.execute(MavenInvoker.java:78)
at org.apache.maven.cling.invoker.LookupInvoker.doInvoke(LookupInvoker.java:166)
at org.apache.maven.cling.invoker.LookupInvoker.invoke(LookupInvoker.java:132)
at org.apache.maven.cling.ClingSupport.run(ClingSupport.java:64)
at org.apache.maven.cling.MavenCling.main(MavenCling.java:49)
at jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
at java.lang.reflect.Method.invoke(Method.java:580)
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: com.thoughtworks.xstream.converters.ConversionException: No converter available
---- Debugging information ----
message : No converter available
type : org.apache.maven.model.WrapperList
converter : com.thoughtworks.xstream.converters.reflection.ReflectionConverter
message[1] : Unable to make field protected transient int java.util.AbstractList.modCount accessible: module java.base does not "opens java.util" to unnamed module @33fec21
-------------------------------
at com.thoughtworks.xstream.core.DefaultConverterLookup.lookupConverterForType(DefaultConverterLookup.java:88)
at com.thoughtworks.xstream.XStream$1.lookupConverterForType(XStream.java:478)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:49)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:44)
at com.thoughtworks.xstream.core.TreeMarshaller.start(TreeMarshaller.java:83)
at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.marshal(AbstractTreeMarshallingStrategy.java:37)
at com.thoughtworks.xstream.XStream.marshal(XStream.java:1303)
at com.thoughtworks.xstream.XStream.marshal(XStream.java:1292)
at com.thoughtworks.xstream.XStream.toXML(XStream.java:1265)
at com.thoughtworks.xstream.XStream.toXML(XStream.java:1252)
at org.apache.maven.plugins.help.EvaluateMojo.toXML(EvaluateMojo.java:358)
at org.apache.maven.plugins.help.EvaluateMojo.handleResponse(EvaluateMojo.java:311)
at org.apache.maven.plugins.help.EvaluateMojo.execute(EvaluateMojo.java:189)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:146)
at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2(MojoExecutor.java:339)
at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute(MojoExecutor.java:310)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:214)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:179)
at org.apache.maven.lifecycle.internal.MojoExecutor$1.run(MojoExecutor.java:168)
at org.apache.maven.plugin.DefaultMojosExecutionStrategy.execute(DefaultMojosExecutionStrategy.java:39)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:165)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:110)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:76)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:60)
at org.apache.maven.lifecycle.internal.DefaultLifecycleStarter.execute(DefaultLifecycleStarter.java:123)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:311)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:225)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:149)
at org.apache.maven.cling.invoker.mvn.MavenInvoker.doExecute(MavenInvoker.java:454)
at org.apache.maven.cling.invoker.mvn.MavenInvoker.execute(MavenInvoker.java:97)
at org.apache.maven.cling.invoker.mvn.MavenInvoker.execute(MavenInvoker.java:78)
at org.apache.maven.cling.invoker.LookupInvoker.doInvoke(LookupInvoker.java:166)
at org.apache.maven.cling.invoker.LookupInvoker.invoke(LookupInvoker.java:132)
at org.apache.maven.cling.ClingSupport.run(ClingSupport.java:64)
at org.apache.maven.cling.MavenCling.main(MavenCling.java:49)
at jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
at java.lang.reflect.Method.invoke(Method.java:580)
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]
```

---
No further details from [MPH-222](https://issues.apache.org/jira/browse/MPH-222?redirect=false)

Start by reproducing the two mvn help:evaluate commands from the issue and read the stack trace through EvaluateMojo.toXML and EvaluateMojo.handleResponse. Investigate how the project.repositories and settings.repositories values are converted, then verify both commands complete without the reported XStream conversion failure and produce their requested output.

Written by the indexing model from the issue text.