core/lib/Drupal/Core/Block/BlockPluginInterface.php | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/core/lib/Drupal/Core/Block/BlockPluginInterface.php b/core/lib/Drupal/Core/Block/BlockPluginInterface.php
index ce1e33f..cd6811a 100644
--- a/core/lib/Drupal/Core/Block/BlockPluginInterface.php
+++ b/core/lib/Drupal/Core/Block/BlockPluginInterface.php
@@ -63,12 +63,10 @@ public function access(AccountInterface $account, $return_as_object = FALSE);
   /**
    * Builds and returns the renderable array for this block plugin.
    *
-   * This must be the final renderable array. Otherwise Block module will not be
-   * able to detect whether this block has no content. (Blocks without content
-   * are not rendered, but if a non-final renderable array is returned — usually
-   * a render array that has #pre_render callbacks defined, to further build the
-   * render array — then Block module cannot determine whether the block has no
-   * content.)
+   * If a block should not be rendered because it has no content, then this
+   * method must also ensure to return no content: it must then only return an
+   * empty array, or an empty array with #cache set (with cacheability metadata
+   * indicating the circumstances for it being empty).
    *
    * @return array
    *   A renderable array representing the content of the block.