## Return Type and Data Filtering { #return-type-and-data-filtering }

Let's continue from the previous example. We wanted to **annotate the function with one type**, but we wanted to be able to return from the function something that actually includes **more data**.

	// what decoding mechanisms must be applied to obtain the object referenced
	// by the Content-Type header field.
	ContentEncoding string

	// Date and time at which the object is no longer able to be cached
	Expires time.Time

	// Cache-Control - Specifies caching behavior along the request/reply chain
	CacheControl string

	// Specify object storage class
	StorageClass string

    return accessibleObject.getAnnotations();
  }

  @Override
  public final Annotation[] getDeclaredAnnotations() {
    return accessibleObject.getDeclaredAnnotations();
  }

  // We ought to be able to implement GenericDeclaration instead its parent AnnotatedElement.
  // That would give us this method declaration. But for some reason, implementing
  // GenericDeclaration leads to weird errors in Android tests:

        if (this.equivalence.equals(that.equivalence)) {
          /*
           * We'll accept that as sufficient "proof" that either equivalence should be able to
           * handle either reference, so it's safe to circumvent compile-time type checking.
           */
          @SuppressWarnings("unchecked")

            //
            // 2. not to cancel any Future the user returned from an AsyncCallable
            //
            // We promise this because, once we cancel that Future, we would no longer be able to
            // tell when any underlying work it is doing is done. Thus, we might start a new task
            // while that underlying work is still running.
            //

         * inside an AbstractIteratorTester<E>, that's implicitly a cast to
         * AbstractIteratorTester<E>.MultiExceptionListIterator. The runtime won't be able to verify
         * the AbstractIteratorTester<E> part, so it's an unchecked cast. We know, however, that the
         * only possible value for the type parameter is <E>, since otherwise the

	defer logger.AuditLog(ctx, w, r, claims)

	// Check auth here (otherwise r.Form will have unexpected values from
	// the call to `parseForm` below), but return failure only after we are
	// able to validate that it is a valid STS request, so that we are able
	// to send an appropriate audit log.
	user, apiErrCode := checkAssumeRoleAuth(ctx, r)

	if err := parseForm(r); err != nil {

   *     the size method
   */
  public static <T extends @Nullable Object> Collection<T> misleadingSizeCollection(int delta) {
    // It would be nice to be able to return a real concurrent
    // collection like ConcurrentLinkedQueue, so that e.g. concurrent
    // iteration would work, but that would not be GWT-compatible.

            assertTrue(resource.exists(), "Resource should exist");
            assertTrue(resource.isFile(), "Should be a file");
            assertTrue(resource.canWrite(), "Should be writable");

            // Should be able to perform file operations
            assertDoesNotThrow(() -> {
                resource.setReadOnly();
                resource.setReadWrite();
                resource.setAttributes(0x20);

This can save everyone a lot of time and frustration.

For any non-trivial change, we need to be able to answer these questions:

* Why is this change done? What's the use case?
* For user-facing features, what will the API look like?
* What test cases should it have? What could go wrong?