<p>
The built-in functions <code>append</code> and <code>copy</code> assist in
common slice operations.
For both functions, the result is independent of whether the memory referenced
by the arguments overlaps.
</p>

<p>
The <a href="#Function_types">variadic</a> function <code>append</code>
appends zero or more values <code>x</code> to a slice <code>s</code> of

    assertThat(expected).hasMessageThat().contains("connected");

    // adjacent below
    assertEquals(Range.closedOpen(4, 4), range.intersection(Range.closedOpen(2, 4)));

    // overlap below
    assertEquals(Range.closed(4, 6), range.intersection(Range.closed(2, 6)));

    // enclosed with same start
    assertEquals(Range.closed(4, 6), range.intersection(Range.closed(4, 6)));

* Some public APIs have incorrect nullability annotations (both overly restrictive and overly permissive)

While there are competing ways to represent absence (`Optional`, "Null Object" pattern, method overloads),
it is unlikely that we'll be able to remove `null` entirely.

After migrating to Java 8, we can use pluggable type checkers to ensure that our annotations are consistent, 
and there are no missing null checks.

   * Overlapping ranges and empty ranges are forbidden, though adjacent ranges are permitted and
   * will be merged.
   *
   * @throws IllegalArgumentException if any ranges overlap or are empty
   * @since 21.0
   */
  public static <C extends Comparable<?>> ImmutableRangeSet<C> copyOf(Iterable<Range<C>> ranges) {
    return new ImmutableRangeSet.Builder<C>().addAll(ranges).build();
  }

    assertThat(expected).hasMessageThat().contains("connected");

    // adjacent below
    assertEquals(Range.closedOpen(4, 4), range.intersection(Range.closedOpen(2, 4)));

    // overlap below
    assertEquals(Range.closed(4, 6), range.intersection(Range.closed(2, 6)));

    // enclosed with same start
    assertEquals(Range.closed(4, 6), range.intersection(Range.closed(4, 6)));

  }

  // 'test' to demonstrate some potentially ambiguous overloads.  This 'test' is kind of strange,
  // but essentially each line will be a call to a Preconditions method that, but for a documented
  // change would be a compiler error.
  // See https://docs.oracle.com/javase/specs/jls/se25/html/jls-15.html#jls-15.12.2 for the spec on
  // how javac selects overloads
  @SuppressWarnings("null")
  public void overloadSelection() {

  }

  // 'test' to demonstrate some potentially ambiguous overloads.  This 'test' is kind of strange,
  // but essentially each line will be a call to a Preconditions method that, but for a documented
  // change would be a compiler error.
  // See https://docs.oracle.com/javase/specs/jls/se25/html/jls-15.html#jls-15.12.2 for the spec on
  // how javac selects overloads
  @SuppressWarnings("null")
  public void overloadSelection() {

   * Overlapping ranges and empty ranges are forbidden, though adjacent ranges are permitted and
   * will be merged.
   *
   * @throws IllegalArgumentException if any ranges overlap or are empty
   * @since 21.0
   */
  public static <C extends Comparable<?>> ImmutableRangeSet<C> copyOf(Iterable<Range<C>> ranges) {
    return new ImmutableRangeSet.Builder<C>().addAll(ranges).build();
  }

Also, the best approach was to use already existing standards.

So, before even starting to code **FastAPI**, I spent several months studying the specs for OpenAPI, JSON Schema, OAuth2, etc. Understanding their relationship, overlap, and differences.

## Design { #design }

Then I spent some time designing the developer "API" I wanted to have as a user (as a developer using FastAPI).

   * serializable.
   *
   * <p><b>Java 8+ users:</b> Use {@code thisComparator.thenComparing(secondaryComparator)} instead.
   * Depending on what {@code secondaryComparator} is, one of the other overloads of {@code
   * thenComparing} may be even more useful.
   */
  public <U extends T> Ordering<U> compound(Comparator<? super U> secondaryComparator) {