* Discards any cached values for keys {@code keys}.
   *
   * @since 11.0
   */
  // For discussion of <? extends Object>, see getAllPresent.
  void invalidateAll(Iterable<? extends Object> keys);

  /** Discards all entries in the cache. */
  void invalidateAll();

  /** Returns the approximate number of entries in this cache. */
  long size();

  /**

    private static void dropVirtualFileSystemIfRequested(InternalOptions options, BuildLifecycleAwareVirtualFileSystem virtualFileSystem) {
        if (VirtualFileSystemServices.isDropVfs(options)) {
            virtualFileSystem.invalidateAll();
        }
    }

        }

        if (!warnings.isEmpty()) {
            LOGGER.info("Invalidating VFS because {} failed validation", work.getDisplayName());
            virtualFileSystem.invalidateAll();
        }

        return delegate.execute(work, new ValidationFinishedContext(context, warnings));
    }

            convertToSingleLine(renderMinimalInformationAbout(warnings.first(), false, false)) == expectedWarning
        })
        1 * virtualFileSystem.invalidateAll()

        then:
        1 * delegate.execute(work, { ValidationFinishedContext context ->
            convertToSingleLine(renderMinimalInformationAbout(context.validationProblems.first(), false, false)) == expectedWarning

      Key key = new Key(1);
      String value = key.toString();
      assertSame(value, cache.getUnchecked(key));
      assertFalse(cache.asMap().isEmpty());
      cache.invalidateAll();
      assertEquals(0, cache.size());
      assertTrue(cache.asMap().isEmpty());
      assertFalse(cache.asMap().containsKey(key));
      assertFalse(cache.asMap().containsValue(value));
    }
  }