title: Maven 3 warnings about build.plugins.plugin.version
body: <p>Since I updated to Maven 3 I get the following warning messages at each build :</p>
  
  <p>How can I get rid of these warnings?</p>
  
  <pre><code>[INFO] Scanning for projects...
  [WARNING] 
  [WARNING] Some problems were encountered while building the effective model for proj:id:jar:3.1
  [WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-javadoc-plugin is missing. @ line 195, column 15
  [WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-compiler-plugin is missing. @ line 204, column 15
  [WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-surefire-plugin is missing. @ line 227, column 15
  [WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-jar-plugin is missing. @ line 215, column 15
  [WARNING] 'reporting.plugins.plugin.version' for org.codehaus.mojo:jdepend-maven-plugin is missing. @ line 271, column 15
  [WARNING] 
  [WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
  [WARNING] 
  [WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
  </code></pre>