bug#31943: Some Maven bugs

bug#31943: Some Maven bugs

[Björn Höfling]

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Maven is now part of Guix, yeah! I gave it a try and found some bugs
which I post collectively here. I don't know yet where exactly they
come from and if they are trivial or not to fix. So if you think they
should better go each into a separate bug report, please separate them.

For reference, I'm on Ubuntu with:

$> guix pull --list-generations | tail --lines=6
guile: warning: failed to install locale
warning: failed to install locale: Invalid argument

Generation 2    Jun 22 2018 21:53:40    (current)
  guix 18ab54d
    repository URL: https://git.savannah.gnu.org/git/guix.git
    commit: 18ab54d4a2aaf932b14e69c30650c1d2c4db33c7


1) The following propagated inputs are used from bash scripts
and are missing: which, coreutils

$> guix environment -C --ad-hoc maven icedtea@3:jdk -- mvn 
/gnu/store/sk23y72hma8x6n5ch6xqgql1q93dg7if-profile/bin/mvn: line 46: uname: command not found
/gnu/store/sk23y72hma8x6n5ch6xqgql1q93dg7if-profile/bin/mvn: line 56: ls: command not found
/gnu/store/sk23y72hma8x6n5ch6xqgql1q93dg7if-profile/bin/mvn: line 57: expr: command not found
/gnu/store/sk23y72hma8x6n5ch6xqgql1q93dg7if-profile/bin/mvn: line 58: expr: command not found
/gnu/store/sk23y72hma8x6n5ch6xqgql1q93dg7if-profile/bin/mvn: line 61: dirname: command not found
/gnu/store/sk23y72hma8x6n5ch6xqgql1q93dg7if-profile/bin/mvn: line 67: dirname: command not found
/gnu/store/sk23y72hma8x6n5ch6xqgql1q93dg7if-profile/bin/mvn: line 94: which: command not found
The JAVA_HOME environment variable is not defined correctly
This environment variable is needed to run this program
NB: JAVA_HOME should point to a JDK not a JRE

2) There is something wrong with the version output:

$> guix environment -C --ad-hoc maven icedtea@3:jdk coreutils which --
mvn -version

null <version unknown>
${distributionShortName} home: /gnu/store/a19m087lz9fg4c2aplvdlm1y2iiibjdb-maven-3.5.3
Java version: 1.8.0_161, vendor: Oracle Corporation
Java home: /gnu/store/7dah2ha88f4sxakpgdlbfn6mvs842j6w-icedtea-3.7.0-jdk/jre
Default locale: en_US, platform encoding: ANSI_X3.4-1968
OS name: "linux", version: "4.4.0-128-generic", arch: "amd64", family: "unix"


Compare this to my "native" Ubuntu maven:

$> /usr/bin/mvn -version
Apache Maven 3.3.9
Maven home: /usr/share/maven
Java version: 1.8.0_161, vendor: Oracle Corporation
Java home: /gnu/store/8yfdmh7hsnfq87ddcyjz5nxk5f208pmc-icedtea-3.7.0-jdk/jre
Default locale: en_US, platform encoding: ANSI_X3.4-1968
OS name: "linux", version: "4.4.0-128-generic", arch: "amd64", family: "unix"


3) The -version part is already handled by Java code. So I tried to
debug Maven remotely from Eclipse, but it failed with a message saying
that debug symbols were missing. I want to verify this again, but could
this be a problem of the ant-build-system removing debug symbols?

4) I cannot use icedteaX (x \in {1,2}) (i.e. X=2 means JDK 1.7) with
Maven. Is this a bug or a fact?

$> guix environment -C --ad-hoc maven icedtea@2:jdk coreutils which --
mvn -version

Exception in thread "main" java.lang.UnsupportedClassVersionError: org/apache/maven/cli/MavenCli : Unsupported major.minor version 52.0
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:803)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:442)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:64)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:354)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:348)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:347)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:312)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:412)
        at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass(Unknown Source)
        at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(Unknown Source)
        at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(Unknown Source)
        at org.codehaus.plexus.classworlds.launcher.Launcher.getMainClass(Unknown Source)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Unknown Source)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Unknown Source)
        at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Unknown Source)
        at org.codehaus.plexus.classworlds.launcher.Launcher.main(Unknown Source)

Version 52.0 means Java 1.8. I think this is because we are now building
all Java packages with ant-build-system with Icedtea@3 and letting it
output Java8 code. Right?

If this is the case anyway, we don't have any chance to choose a JDK to
run maven with (if we choose from Guix, not from other locations).
Should we then add icedtea@3 as a propagated input to maven? Then a
user can directly use Maven and doesn't have to think of installing a
JDK first. Mhm, maybe too strict and too heavy in size?



From now on I'm in a container with a fresh .m2 directory,
assuming "mvn-home" is an empty directory:

guix environment -C -N --share=mvn-home/=/home/bjoern/.m2 --ad-hoc maven coreutils which icedtea@3:jdk


5) Maven complains about the logger output:

$ENV> mvn clean install
[WARNING] The SLF4J binding actually used is not supported by Maven: org.slf4j.impl.SimpleLoggerFactory
[WARNING] Maven supported bindings are:
[INFO] Scanning for projects...
[...]


When looking at the package definition of maven, I find in the inputs:

       ;; TODO: replace with maven-slf4j-provider
       ("java-slf4j-simple" ,java-slf4j-simple)))

Is this comment related to the WARNING? Will it go away with
maven-slf4j-provider?


6) Maven does not compile Java 1.8 code.

To reproduce this, build any Maven project that has either source or
target language version set to 1.8:

<properties>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
</properties>

As our Maven mostly works, you can just use:

$ENV> mvn archetype:generate

to create a new Maven project. Edit the pom.xml to set the versions.

Then [I head some problems with tests, so skipping them here]:

$ENV> mvn clean install -Dmvn.tests.skip=true -X -e

[..]

[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.171 s
[INFO] Finished at: 2018-06-22T22:17:21Z
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.7.0:compile (default-compile) on project tst2: Fatal error compiling: invalid source release: 1.8 -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.7.0:compile (default-compile) on project tst2: Fatal error compiling
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(Unknown Source)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(Unknown Source)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(Unknown Source)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(Unknown Source)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(Unknown Source)
	at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(Unknown Source)
	at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(Unknown Source)
	at org.apache.maven.DefaultMaven.doExecute(Unknown Source)
	at org.apache.maven.DefaultMaven.doExecute(Unknown Source)
	at org.apache.maven.DefaultMaven.execute(Unknown Source)
	at org.apache.maven.cli.MavenCli.execute(Unknown Source)
	at org.apache.maven.cli.MavenCli.doMain(Unknown Source)
	at org.apache.maven.cli.MavenCli.main(Unknown Source)
	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(Unknown Source)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Unknown Source)
	at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Unknown Source)
	at org.codehaus.plexus.classworlds.launcher.Launcher.main(Unknown Source)
Caused by: org.apache.maven.plugin.MojoExecutionException: Fatal error compiling
	at org.apache.maven.plugin.compiler.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:1086)
	at org.apache.maven.plugin.compiler.CompilerMojo.execute(CompilerMojo.java:168)
	at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(Unknown Source)
	... 21 more
Caused by: org.codehaus.plexus.compiler.CompilerException: invalid source release: 1.8
	at org.codehaus.plexus.compiler.javac.JavaxToolsCompiler.compileInProcess(JavaxToolsCompiler.java:173)
	at org.codehaus.plexus.compiler.javac.JavacCompiler.performCompile(JavacCompiler.java:174)
	at org.apache.maven.plugin.compiler.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:1075)
	... 23 more
Caused by: java.lang.IllegalArgumentException: invalid source release: 1.8
	at com.sun.tools.javac.main.RecognizedOptions$GrumpyHelper.error(RecognizedOptions.java:88)
	at com.sun.tools.javac.main.RecognizedOptions$9.process(RecognizedOptions.java:348)
	at com.sun.tools.javac.api.JavacTool.processOptions(JavacTool.java:242)
	at com.sun.tools.javac.api.JavacTool.getTask(JavacTool.java:199)
	at com.sun.tools.javac.api.JavacTool.getTask(JavacTool.java:68)
	at org.codehaus.plexus.compiler.javac.JavaxToolsCompiler.compileInProcess(JavaxToolsCompiler.java:125)
	... 25 more
[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/MojoExecutionException


7) I have some trouble executing the tests. This is indeterministic (!),
sometimes is is successful, sometimes I get an error:

$ENV> mvn clean install -X -e -B>stacktrace.log 2>&1; echo $?

[..]

[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running de.xxx.AppTest
[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 0, Failures: 0, Errors: 0, Skipped: 0
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.981 s
[INFO] Finished at: 2018-06-22T22:27:49Z
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.20.1:test (default-test) on project tst2: There are test failures.
[ERROR] 
[ERROR] Please refer to /home/bjoern/x/z/tst2/target/surefire-reports for the individual test results.
[ERROR] Please refer to dump files (if any exist) [date]-jvmRun[N].dump, [date].dumpstream and [date]-jvmRun[N].dumpstream.
[ERROR] The forked VM terminated without properly saying goodbye. VM crash or System.exit called?
[ERROR] Command was /bin/sh -c cd /home/bjoern/x/z/tst2 && /gnu/store/7dah2ha88f4sxakpgdlbfn6mvs842j6w-icedtea-3.7.0-jdk/jre/bin/java -jar /home/bjoern/x/z/tst2/target/surefire/surefirebooter4025948542605868366.jar /home/bjoern/x/z/tst2/target/surefire 2018-06-22T22-27-48_542-jvmRun1 surefire4165566371678934740tmp surefire_02394075698289798736tmp
[ERROR] Error occurred in starting fork, check output in log
[ERROR] Process Exit Code: 1
[ERROR] org.apache.maven.surefire.booter.SurefireBooterForkException: The forked VM terminated without properly saying goodbye. VM crash or System.exit called?
[ERROR] Command was /bin/sh -c cd /home/bjoern/x/z/tst2 && /gnu/store/7dah2ha88f4sxakpgdlbfn6mvs842j6w-icedtea-3.7.0-jdk/jre/bin/java -jar /home/bjoern/x/z/tst2/target/surefire/surefirebooter4025948542605868366.jar /home/bjoern/x/z/tst2/target/surefire 2018-06-22T22-27-48_542-jvmRun1 surefire4165566371678934740tmp surefire_02394075698289798736tmp
[ERROR] Error occurred in starting fork, check output in log
[ERROR] Process Exit Code: 1
[ERROR] 	at org.apache.maven.plugin.surefire.booterclient.ForkStarter.fork(ForkStarter.java:686)
[ERROR] 	at org.apache.maven.plugin.surefire.booterclient.ForkStarter.fork(ForkStarter.java:535)
[ERROR] 	at org.apache.maven.plugin.surefire.booterclient.ForkStarter.run(ForkStarter.java:280)
[ERROR] 	at org.apache.maven.plugin.surefire.booterclient.ForkStarter.run(ForkStarter.java:245)
[ERROR] 	at org.apache.maven.plugin.surefire.AbstractSurefireMojo.executeProvider(AbstractSurefireMojo.java:1124)
[ERROR] 	at org.apache.maven.plugin.surefire.AbstractSurefireMojo.executeAfterPreconditionsChecked(AbstractSurefireMojo.java:954)
[ERROR] 	at org.apache.maven.plugin.surefire.AbstractSurefireMojo.execute(AbstractSurefireMojo.java:832)
[ERROR] 	at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(Unknown Source)
[ERROR] 	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(Unknown Source)
[ERROR] 	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(Unknown Source)
[ERROR] 	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(Unknown Source)
[ERROR] 	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(Unknown Source)
[ERROR] 	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(Unknown Source)
[ERROR] 	at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(Unknown Source)
[ERROR] 	at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(Unknown Source)
[ERROR] 	at org.apache.maven.DefaultMaven.doExecute(Unknown Source)
[ERROR] 	at org.apache.maven.DefaultMaven.doExecute(Unknown Source)
[ERROR] 	at org.apache.maven.DefaultMaven.execute(Unknown Source)
[ERROR] 	at org.apache.maven.cli.MavenCli.execute(Unknown Source)
[ERROR] 	at org.apache.maven.cli.MavenCli.doMain(Unknown Source)
[ERROR] 	at org.apache.maven.cli.MavenCli.main(Unknown Source)
[ERROR] 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[ERROR] 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[ERROR] 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[ERROR] 	at java.lang.reflect.Method.invoke(Method.java:498)
[ERROR] 	at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Unknown Source)
[ERROR] 	at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Unknown Source)
[ERROR] 	at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Unknown Source)
[ERROR] 	at org.codehaus.plexus.classworlds.launcher.Launcher.main(Unknown Source)
[ERROR] -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.20.1:test (default-test) on project tst2: There are test failures.
[..]




8) BTW maven is NOT creating a reproducible output. That's important if
you want to use it to as a build tool for Guix:

$ENV> jar tvvf
~/.m2/repository/de/xxx/tst2/1.0-SNAPSHOT/tst2-1.0-SNAPSHOT.jar

 110 Fri Jun 22 22:29:26 GMT 2018 META-INF/MANIFEST.MF
   0 Fri Jun 22 22:29:26 GMT 2018 META-INF/



That's it for now. 

Björn

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bug#31943: Some Maven bugs

[Julien Lepiller]

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Le Sat, 23 Jun 2018 00:39:35 +0200,
Björn Höfling <bjoern.hoefling@bjoernhoefling.de> a écrit :

> Maven is now part of Guix, yeah! I gave it a try and found some bugs
> which I post collectively here. I don't know yet where exactly they
> come from and if they are trivial or not to fix. So if you think they
> should better go each into a separate bug report, please separate
> them.
> 
> For reference, I'm on Ubuntu with:
> 
> $> guix pull --list-generations | tail --lines=6  
> guile: warning: failed to install locale
> warning: failed to install locale: Invalid argument
> 
> Generation 2    Jun 22 2018 21:53:40    (current)
>   guix 18ab54d
>     repository URL: https://git.savannah.gnu.org/git/guix.git
>     commit: 18ab54d4a2aaf932b14e69c30650c1d2c4db33c7
> 
> 
> 1) The following propagated inputs are used from bash scripts
> and are missing: which, coreutils
> 
> 2) There is something wrong with the version output:

Fixed with 7504f3c3d3a2fbd0f901757a9bd3175e424c11ca and
e27c43d94e23daf6b114b03688a51c924890a286 :)


> [...]
> 
> 3) The -version part is already handled by Java code. So I tried to
> debug Maven remotely from Eclipse, but it failed with a message saying
> that debug symbols were missing. I want to verify this again, but
> could this be a problem of the ant-build-system removing debug
> symbols?

I think our ant-build-system doesn't add debugging symbols to our java
packages. That's where it should be fixed (if we want to fix it?)

> 
> 4) I cannot use icedteaX (x \in {1,2}) (i.e. X=2 means JDK 1.7) with
> Maven. Is this a bug or a fact?
> 

This is because some of the dependencies cannot be built without java8.
I think there is an option in ant to build with a new jdk but stay
compatible with older jdks. Our ant-build-system should probably use
that.

> [...]
> 
> 5) Maven complains about the logger output:
> 
> Is this comment related to the WARNING? Will it go away with
> maven-slf4j-provider?

Exactly.

> 
> 
> 6) Maven does not compile Java 1.8 code.
> 

Ok, this is unexpected, and that's what I'll be working on next.

> 
> 
> 7) I have some trouble executing the tests. This is indeterministic
> (!), sometimes is is successful, sometimes I get an error:
> 

Weird too.

> 
> 
> 8) BTW maven is NOT creating a reproducible output. That's important
> if you want to use it to as a build tool for Guix:
> 

I think this is expected. I've seen a bug report about that, but can't
find it anymore. We could reuse the repack-jar phase from the
ant-build-system though.

> 
> Björn

Thank you for your reports!


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bug#31943: Some Maven bugs

[Björn Höfling]

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On Sat, 23 Jun 2018 12:20:33 +0200
Julien Lepiller <julien@lepiller.eu> wrote:

> Le Sat, 23 Jun 2018 00:39:35 +0200,
> Björn Höfling <bjoern.hoefling@bjoernhoefling.de> a écrit :
> 

> > 1) The following propagated inputs are used from bash scripts
> > and are missing: which, coreutils
> > 
> > 2) There is something wrong with the version output:  
> 
> Fixed with 7504f3c3d3a2fbd0f901757a9bd3175e424c11ca and
> e27c43d94e23daf6b114b03688a51c924890a286 :)

That was quick :-) Thanks.


> > 4) I cannot use icedteaX (x \in {1,2}) (i.e. X=2 means JDK 1.7) with
> > Maven. Is this a bug or a fact?
> >   
> 
> This is because some of the dependencies cannot be built without
> java8. I think there is an option in ant to build with a new jdk but
> stay compatible with older jdks. Our ant-build-system should probably
> use that.

Maven requires JDK 1.7 or above to run
(https://maven.apache.org/download.cgi). So support for JDK7 should
work, JDK6 not. Forget icedtea@1.

I see that some of the dependencies like maven-resolver-util are
explicitly setting the #jdk to icedtea-8. So no wonder they produce JDK
1.8 code.

For the <javac ..> task, there is target property, see docs here:

https://ant.apache.org/manual/Tasks/javac.html

You can also set the option ant.build.javac.target:

https://ant.apache.org/manual/javacprops.html#target

We could introduce the latter one in the ant-build-system, with nothing
set being the default (i.e. the output of the used JDK).


Björn

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bug#31943: Some Maven bugs

[Julien Lepiller]

Le Sat, 23 Jun 2018 00:39:35 +0200,
Björn Höfling <bjoern.hoefling@bjoernhoefling.de> a écrit :

> Maven is now part of Guix, yeah! I gave it a try and found some bugs
> which I post collectively here. I don't know yet where exactly they
> come from and if they are trivial or not to fix. So if you think they
> should better go each into a separate bug report, please separate
> them.
> 
> [...]
> 
> 6) Maven does not compile Java 1.8 code.
> 

This should be fixed in 892a5647debc7fe8eafac4f725c46134eb085b63.

I was cramming the whole set of dependencies for maven in the
classpath, but it seems it doesn't play well with downloaded plugins.
Now I generated a m2.conf file with multiple "load" lines to tell
plexus-classworlds where to find the required jar files.

> 
> 
> 7) I have some trouble executing the tests. This is indeterministic
> (!), sometimes is is successful, sometimes I get an error:
> 

So I've tested this, and it turns out it's not our package's fault: it
fails undeterministically also when using the system's maven. I fixed
it by downgrading maven-surefire-plugin version to 2.20 instead of
2.20.1.

Thank you for your reports! Do you think we can close this report now?

bug#31943: Some Maven bugs

[Björn Höfling]

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Hi Julien,

On Wed, 4 Jul 2018 22:06:08 +0200
Julien Lepiller <julien@lepiller.eu> wrote:

> Le Sat, 23 Jun 2018 00:39:35 +0200,
> Björn Höfling <bjoern.hoefling@bjoernhoefling.de> a écrit :
> 
> > Maven is now part of Guix, yeah! I gave it a try and found some bugs
> > which I post collectively here. I don't know yet where exactly they
> > come from and if they are trivial or not to fix. So if you think
> > they should better go each into a separate bug report, please
> > separate them.
> > 
> > [...]
> > 
> > 6) Maven does not compile Java 1.8 code.
> >   
> 
> This should be fixed in 892a5647debc7fe8eafac4f725c46134eb085b63.
> 
> I was cramming the whole set of dependencies for maven in the
> classpath, but it seems it doesn't play well with downloaded plugins.
> Now I generated a m2.conf file with multiple "load" lines to tell
> plexus-classworlds where to find the required jar files.

Great, works!


> > 7) I have some trouble executing the tests. This is indeterministic
> > (!), sometimes is is successful, sometimes I get an error:
> >   
> 
> So I've tested this, and it turns out it's not our package's fault: it
> fails undeterministically also when using the system's maven. I fixed
> it by downgrading maven-surefire-plugin version to 2.20 instead of
> 2.20.1.

I wondered that there is no commit for this an then realized that I have
to do that on my own in the pom.xml for each project, because Maven will
download its plugins:

<build> 
  <pluginManagement>
    <plugin>
      <artifactId>maven-surefire-plugin</artifactId>
      <version>2.20</version>
    </plugin>
     ...
</build>

 
> Thank you for your reports! Do you think we can close this report now?

Thanks for fixing so quickly. Yes, closing with this message.

Björn

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