code: protected URL getCompleteRootUrl()
          throws InstallationException
      {
          try {
              final URL url;
              if (this.application.getRootPackageName() == null) {
                  url = this.application.getRootUrl();
              } else {
                  url = new URL(this.application.getRootUrl(), this.application.getRootPackageName());
              }
              return url;
          } catch (final MalformedURLException e)  {
              throw new InstallationException("Root url could not be prepared", e);
          }
      }
docs: Returns the complete root URL so that resources in the installation
  package could be fetched. If an installation from the source directory
  is done, the {@link Application#getRootUrl() root URL} is directly
  returned, in the case that an installation is done from a JAR container
  the {@link Application#getRootUrl() root URL} is appended with the name
  of the {@link Application#getRootPackageName() root package name}.
  
  @return complete root URL
  @throws InstallationException if complete root URL could not be prepared