Setting project for eclipse using maven

Question

I'm trying to start modifying an existing application with Eclipse. Actually I had it working before, but I deleted the project, and now with "mvn eclipse:eclipse" I get the following:

[INFO] Resource directory's path matches an existing source directory. Resources will be merged with the source directory src/main/resources
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Request to merge when 'filtering' is not identical. Original=resource src/main/resources: output=target/classes, include=[atlassian-plugin.xml], exclude=[**/*.java], test=false, filtering=true,
 merging with=resource src/main/resources: output=target/classes, include=[], exclude=[atlassian-plugin.xml|**/*.java], test=false, filtering=false
[INFO] ------------------------------------------------------------------------
[INFO] Trace
org.apache.maven.lifecycle.LifecycleExecutionException: Request to merge when 'filtering' is not identical. Original=resource src/main/resources: output=target/classes, include=[atlassian-plugin.xml],
 exclude=[**/*.java], test=false, filtering=true, merging with=resource src/main/resources: output=target/classes, include=[], exclude=[atlassian-plugin.xml|**/*.java], test=false, filtering=false
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:583)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeStandaloneGoal(DefaultLifecycleExecutor.java:512)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:482)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:330)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:291)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:142)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:336)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:129)
        at org.apache.maven.cli.MavenCli.main(MavenCli.java:287)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        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.MojoExecutionException: Request to merge when 'filtering' is not identical. Original=resource src/main/resources: output=target/classes, include=[atlassian-plugin.xm
l], exclude=[**/*.java], test=false, filtering=true, merging with=resource src/main/resources: output=target/classes, include=[], exclude=[atlassian-plugin.xml|**/*.java], test=false, filtering=false
        at org.apache.maven.plugin.eclipse.EclipseSourceDir.merge(EclipseSourceDir.java:302)
        at org.apache.maven.plugin.eclipse.EclipsePlugin.extractResourceDirs(EclipsePlugin.java:1605)
        at org.apache.maven.plugin.eclipse.EclipsePlugin.buildDirectoryList(EclipsePlugin.java:1490)
        at org.apache.maven.plugin.eclipse.EclipsePlugin.createEclipseWriterConfig(EclipsePlugin.java:1180)
        at org.apache.maven.plugin.eclipse.EclipsePlugin.writeConfiguration(EclipsePlugin.java:1043)
        at org.apache.maven.plugin.ide.AbstractIdeSupportMojo.execute(AbstractIdeSupportMojo.java:511)
        at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:451)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:558)
        ... 16 more

Answer 1

Would this make it better?

 mvn org.apache.maven.plugins:maven-eclipse-plugin:2.6:eclipse

This tells maven to use version 2.6 (which still works) instead of the default 2.7 (which doesn't).
You'll have to issue the command like this every time, so it's a little inconvenient whereas the file changes above should result in a one-time fix, but this way you don't risk accidentally breaking something else and you don't have to go looking for files.
If you can't remember the command syntax, copy it into a text file for easier reference.

See this thread.

It does mention a recent change in the Maven Eclipse Plugin:

• MECLIPSE-551 regression - Resources are excluded if resource dir equals source dir
• MECLIPSE-551 Jira ticket

Answer 2

I think VonC's answer is the right one (+1) if you are using the eclipse:eclipse goal. Personally I find it more trouble than it's worth and instead use m2eclipse to manage the dependencies, committing the eclipse metadata files to SCM.

To avoid having to invoke eclipse:eclipse with the fully-qualified name as VonC suggests, you can configure the plugin in your pom to use the exact version. This is good practice anyway.

In the pom, specify the plugin as follows:

<build>
...
  <plugins>
  ...
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-eclipse-plugin</artifactId>
      <version>2.6</version>
    </plugin>
  </plugins>
</build>

Then whenever you invoke the eclipse plugin, version 2.6 will be used.