metadata plugin group id

[i....@nki.nl]

Hi,
I'm trying to use the maven-vaadin-plugin (however my question probably applies to all plugins) and i get:
 ------------------------------------------------------------------------
 [INFO] The plugin 'org.apache.maven.plugins:maven-vaadin-plugin' does not exist or no valid version could be found

 Why is maven looking for the vaadin plugin in org.apache.maven.plugins while my pom clearly says:
  <plugin>
            <groupId>com.vaadin</groupId>
            <artifactId>vaadin-maven-plugin</artifactId>
            <version>1.0.0</version>
            <executions>
                <execution>
                    <configuration>
                        <!-- if you don't specify any modules, the plugin will find them -->
                        <!--
                        <modules>
                            <module>${package}.gwt.MyWidgetSet</module>
                        </modules>
                        -->
                    </configuration>
                    <goals>
                        <goal>update-widgetset</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>

If i add the plugin as a dependency, it is found and downloaded in the \.m2\repository\com\vaadin\vaadin-maven-plugin\1.0.0 directory.
But when i look in the maven plugin directory in my local repository, there it is: maven-vaadin-plugin and its maven-metadata-central.xml files says:
<?xml version="1.0" encoding="UTF-8"?>
<metadata>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-vaadin-plugin</artifactId>
</metadata>

This file is renewed every time i run maven (i tried removing it). So where does this information come from and why is the vaadin plugin grouped with org.apache.maven.plugins when my pom says com.vaadin?
Any insights much appreciated.

Ivana Čače
Medewerker Informatievoorziening KFI

NKI-AVL

Afdeling Radiotherapie
Antoni van Leeuwenhoek ziekenhuis / Nederlands Kanker Instituut
Plesmanlaan 121, 1066 CX Amsterdam
T:  +31-20-512-8006
E: i.cace@nki.nl<ma...@nki.nl>