Parent properties inside maven antrun plugin

<properties>
 <main.basedir>${project.parent.basedir}</main.basedir>
    ...
</properties>

<plugins>
 <plugin>
  <artifactId>maven-antrun-plugin</artifactId>
  <executions>
   <execution>
    <id>render-parameter-sql</id>
    <phase>validate</phase>
    <goals>
     <goal>run</goal>
    </goals>
    <configuration>
     <tasks>
      <echoproperties/>
     </tasks>
    </configuration>
   </execution>
  </executions>
 </plugin>
</plugins>

main:
[echoproperties] #Ant properties
[echoproperties] #Thu Oct 28 09:32:13 CEST 2010
[echoproperties] ant.core.lib=C:\Users\gaborl\.m2\repository\org\apache\ant\ant\1.8.1\ant-1.8.1.jar
...
[echoproperties] main.basedir=${project.parent.basedir}
[echoproperties] maven.dependency.antlr.antlr.jar.path=C:\Users\gaborl\.m2\repository\antlr\antlr\2.7.6\antlr-2.7.6.jar

<plugin>
  <groupId>org.codehaus.gmaven</groupId>
  <artifactId>gmaven-plugin</artifactId>
  <version>1.3</version>
  <executions>
    <execution>
      <id>set-custom-property</id>
      <phase>validate</phase>
      <goals>
        <goal>execute</goal>
      </goals>
      <configuration>
        <source>
          project.properties.setProperty('main.basedir', project.parent.basedir.toString())
        </source>
      </configuration>
    </execution>
  </executions>
</plugin>
<plugin>
  <artifactId>maven-antrun-plugin</artifactId>
  <version>1.6</version>
  <executions>
    <execution>
      <id>render-parameter-sql</id>
      <phase>validate</phase>
      <goals>
        <goal>run</goal>
      </goals>
      <configuration>
        <target>
          <echo>project.artifactId        : ${project.artifactId}</echo>
          <echo>project.parent.basedir    : ${project.parent.basedir}</echo>
          <echo>main.basedir              : ${main.basedir}</echo>
          <echo>project.basedir           : ${project.basedir}</echo>
          <echo>project.build.directory   : ${project.build.directory}</echo>
        </target>
      </configuration>
    </execution>
  </executions>
</plugin>