## Technical Details

Just a technical detail for the curious nerds. 🤓

Underneath, in the ASGI technical specification, this is part of the <a href="https://asgi.readthedocs.io/en/latest/specs/lifespan.html" class="external-link" target="_blank">Lifespan Protocol</a>, and it defines events called `startup` and `shutdown`.

/// info

   * That statement compiles only if {@link FluentIterable#concat concat(aIterable, bIterable)}
   * returns a {@link FluentIterable} of elements of an anonymous type whose supertypes are the <a
   * href="https://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.9">intersection</a> of
   * the supertypes of {@code A} and the supertypes of {@code B}.
   */
  public void testConcatIntersectionType() {
    Iterable<A> aIterable = ImmutableList.of();

      // extensive testing
      try {
        return Double.parseDouble(string);
      } catch (NumberFormatException e) {
        // Double.parseDouble has changed specs several times, so fall through
        // gracefully
      }
    }
    return null;
  }