Javadoc of generated sources is not generated when aggregate=true

Hi,

If have a multi-module project :
pom.xml

I generate source in moduleB.

1) If I run mvn javadoc:javadoc in moduleB directory, it works (javadoc of the generated class is created)
2) If I run mvn javadoc:javadoc from the root directory, with aggregate=false, it works (javadoc is in moduleB/target/site/apidocs)
3) If I run mvn javadoc:javadoc from the root directory, with aggregate=true, it doesn't works (javadoc is in target/site/apidocs but not for the generated class)

Thanks for any help.