private static boolean isPreview(@NotNull ExternalProject externalProject) {
    final Collection<? extends ExternalSourceSet> values = externalProject.getSourceSets().values();
    if (values.isEmpty()) {
      return false;
    }
    else {
      return ContainerUtil.and(values, it -> it.isPreview());
    }
  }
private static boolean isPreview(@NotNull ExternalProject externalProject)