How to make generated classes contain Javadoc from XML Schema documentation

I've never been able to get regular xsd:documentation to be placed in the java source except if and only if it was a Complex Type. Documentation for elements, simple types, etc are ignored.

So, I end up using jxb:javadoc. To do so, include the definition of xmlns:jxb="http://java.sun.com/xml/ns/jaxb" in your <xsd:schema> element.

Add a child to <xsd:complexType> or <xsd: element> or <xsd:attribute>:

<xsd:annotation><xsd:appinfo><jxb:XXX><jxb:javadoc>
  This is my comment for a class/property
</jxb:javadoc></jxb:XXX></xsd:appinfo></xsd:annotation>

Where XXX is either "class" or "property".

For a package you write a child to xsd:schema

<xsd:annotation><xsd:appinfo><jxb:schemaBindings><jxb:package name="com.acme"><jxb:javadoc>
  This is my comment for a package
</jxb:javadoc></jxb:package></jxb:schemaBindings></xsd:appinfo></xsd:annotation>

Writing HTML document requires bracketing with <![CDATA[ --- ]]>

(EDIT: While writing my answer, the question has been edited by the OP so I'm updating it accordingly)

In my case, javadoc was the only target so it was acceptable to use jxb:javadoc. But your update makes perfect sense and, actually, I totally agree with you. Sadly, I never found an ideal solution for the situation you describe (so I'll follow this question very carefully). Maybe you could use something like xframe to generate documentation from xsd:documentation, but this doesn't answer the question.

This just isn't possible with the JAXB reference implementation. Even if you were to try to write an XJC plugin, you'd find that the plugin API is given no reference to the Schema definition, so there's no way to extract this information.

Our only hope is that a future version of JAXB fixes the situation. There's an open feature request here.