code: @Configurable
    public void setSourceExtension(String ext)
      throws ConfigException
    {
      if (! ext.startsWith("."))
        throw new ConfigException(L.l("source-extension '{0}' must begin with '.'",
                                      ext));
      
      _sourceExt = ext;
    }
docs: source-extension: the path extension for source files; defaults to *.java