eclipse pom fix

I think adding this to our project's -impl/pom.xml file fixed the eclipse importing issue:

  <build>
    <pluginManagement>
      <plugins>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>build-helper-maven-plugin</artifactId>
        <executions>
          <execution>
            <id>add-source</id>
            <phase>generate-sources</phase>
            <goals>
              <goal>add-source</goal>
            </goals>
            <configuration>
              <sources>
                <source>${project.build.directory}/generated-sources/java/</source>
              </sources>
            </configuration>
          </execution>
        </executions>
      </plugin>
      </plugins>
    </pluginManagement>
  </build>