Method of

core/src/main/java/org/apache/calcite/runtime/ConsList.java:44–53

Creates a ConsList. It consists of an element pre-pended to another list. If the other list is mutable, creates an immutable copy.

(E first, List<? extends E> rest)

   * It consists of an element pre-pended to another list.
   * If the other list is mutable, creates an immutable copy. */
  public static <E> List<E> of(E first, List<? extends E> rest) {
    if (rest instanceof ConsList
        || rest instanceof ImmutableList
        && !rest.isEmpty()) {
      //noinspection unchecked
      return new ConsList<>(first, (List<E>) rest);
    } else {
      return ImmutableList.<E>builder().add(first).addAll(rest).build();
    }
  }

  private ConsList(E first, List<E> rest) {
    this.first = first;