android/guava/src/com/google/common/collect/ImmutableSet.java
public static <E> ImmutableSet<E> copyOf(E[] elements) {
    switch (elements.length) {
      case 0:
        return of();
      case 1:
        return of(elements[0]);
      default:
        return construct(elements.length, elements.clone());
    }
  }
public static <E> ImmutableSet<E> copyOf(E[] elements) {
    switch (elements.length) {
      case 0:
        return of();
      case 1:
        return of(elements[0]);
      default:
        return construct(elements.length, elements.clone());
    }
  }
Returns an immutable set containing each of {@code elements}, minus duplicates, in the order
each appears first in the source array.

@throws NullPointerException if any of {@code elements} is null
@since 3.0