[jira] [Created] (MNGSITE-519) Update the plugin merge note in lifecycle docs

["Giovanni van der Schelde (Jira)" <ji...@apache.org>]

Giovanni van der Schelde created MNGSITE-519:
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             Summary: Update the plugin merge note in lifecycle docs
                 Key: MNGSITE-519
                 URL: https://issues.apache.org/jira/browse/MNGSITE-519
             Project: Maven Project Web Site
          Issue Type: Improvement
            Reporter: Giovanni van der Schelde


Seeing the warning message in 3.9 and the error message in 4.0.0-alpha-5 I assume this is intended behaviour. However, I couldn't find the tickets or release notes related to it, so it might be a MNG question?

If it is an intended breaking change the docs should probably get updated.

The [docs|https://github.com/apache/maven-site/blob/5c32e14114d2bbf28f958024e37a960bfd7b8121/content/apt/guides/introduction/introduction-to-the-lifecycle.apt#L144] state:
{quote}Multiple instances of the same plugin are grouped to execute together and ordered in Maven 2.0.11 and above
{quote}
Whenever I define the same plugin twice in the {{pom.xml}} it merges the configuration with 3.9 (does give a warning about possible deprecation in higher versions) but fails in 4.0.0-alpha-5 with a clear error message.

{{[ERROR] Some problems were encountered while processing the POMs}}
{{[ERROR] The build could not read 1 project -> [Help 1]}}
{{[ERROR]}}
{{[ERROR]   The project com.giovds:giovds-test-plugin:3.0.0-SNAPSHOT (C:\tmp\maven-sandbox\pom.xml) has 1 error}}
{{[ERROR]     'build.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.apache.maven.plugins:maven-enforcer-plugin @ line 55, column 15}}
{{[ERROR]}}
{{[ERROR] To see the full stack trace of the errors, re-run Maven with the '-e' switch}}
{{[ERROR] Re-run Maven using the '-X' switch to enable verbose output}}
{{[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/ProjectBuildingException]}}

MNGSITE-393 might be related.



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