mvn eclipse plugin missing required source folder

[Davis Ford]

Hello, I have a problem getting the mvn eclipse plugin recognizing a
relative path resource directory.   Using mvn 2.0.6.  The project structure
looks like this:

editor
     ----subprojecta
          -----pom.xml
          -----src
    -----subprojectb
          -----pom.xml
          -----src
    -----conf
         -----some.config.xml
    -----pom.xml

editor is a pom only project that has:

<modules>
  <module>subprojecta</module>
  <module>subprojectb</module>
</modules>

The pom in each subproject has this:

<build>
<resources>
           <resource>
               <directory>../conf</directory>
               <includes>
                   <include>**/*</include>
               </includes>
           </resource>
       </resources>
</build>

This actually seems to work fine at runtime, b/c the code can load the xml
files it needs in each sub-project.  However, if I execute mvn
eclipse:eclipse, I get the build path error "Project subprojecta is missing
required source folder: 'D:\svn\editor\conf'.

Any idea on what I'm doing wrong here?

Regards,
Davis