How do I access maven project version in javadoc overview page?

I am using PDFDoclet with maven-javadoc-plugin and I've come quite a long way with it now. I have the maven and javadoc config almost at a point that is good enough but my immediate problem now is that I can't work out how to push the project version number into the PDF title page.

Before you leap to answer my question by telling me to use maven's <resource> filtering, let me outline why that isn't working.

Filtering works by taking the original file from somewhere in the src folder, doing variable substitution and putting the output in the target folder.

Javadoc works by reading files in src/main/java and src/main/javadoc and AFAIK outputting the results into target. This means filtering is useless for Javadoc since it won't read anything from target

My results show that any maven variables in javadoc comments don't get substituted.

What trick can I use to get those variables substituted into the javadoc?

The solution can't involve filtering the javadoc output after the site:site task, unless resource filtering works on PDFs.

This is the configuration, FWIW:

  <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-javadoc-plugin</artifactId>
    <version>2.10.3</version>
    <configuration>
      <show>package</show>
      <docfilessubdirs>true</docfilessubdirs>
      <tags>
        <tag>
          <name>pdfInclude</name>
          <placement>X</placement>
          <head></head>
        </tag>
      </tags>
    </configuration>
    <reportSets>
      <reportSet>
        <id>PDF</id>
        <reports>
          <report>javadoc</report>
        </reports>
        <configuration>
          <name>PDF</name>
          <description>PDF doc</description>
          <destDir>pdf</destDir>
          <doclet>com.tarsec.javadoc.pdfdoclet.PDFDoclet</doclet>
          <docletPath>${basedir}/pdfdoclet/pdfdoclet-1.0.3-all.jar</docletPath>
          <useStandardDocletOptions>false</useStandardDocletOptions>
          <additionalparam>-pdf my_tech_doc-${project.version}.pdf
            -config ${basedir}/pdfdoclet/pdfdoclet.properties</additionalparam>
        </configuration>
      </reportSet>
    </reportSets>
  </plugin>

and the pdfdoclet.properties:

    # http://pdfdoclet.sourceforge.net/configuration.html
    #
    #Lets the doclet print additional output in the console and to a logfile.
    debug=true 
    #Print "Author" tags
    author=false  
    #Print "Version" tags
    version=true
    #Print "since" tags
    tag.since=true
    #Create summary tables
    summary.table=false
    #Create hyperlinks
    create.links=true
    #Encrypt the PDF file
    encrypted=false
    #Allow printing of the PDF file
    allow.printing=true 
    #Create a bookmark frame
    create.frame=true
    #Print a title page
    api.title.page=true
    api.copyright=None
    api.author=Hansruedi
    #Enables the tag-based filter
    filter=true
    filter.tags=pdfInclude
    font.text.name=resources/arial.ttf
    page.orientation=portrait

The PDFDoclet-specific api.* properties should result in a title page as the first page of the PDF, but it doesn't work. If there is a trick that I've missed here and I could get that title page produced, then that might also allow a solution for this somehow.

Solution

I realised I can do a quick and dirty hack with the maven <resources> functionality:

  <resource>
    <directory>${basedir}/src/main/resources</directory>
    <targetPath>${basedir}/src/main/javadoc</targetPath>
    <filtering>true</filtering>
    <includes>
      <include>**/overview.html</include>
    </includes>
  </resource>

This copies my overview.html and filters it, outputting it into the javadoc source directory.

The dirtiness is that this filtered version could then accidentally end up under version control, although using svn I can add it to the ignore list.