diff --git a/core/lib/Drupal/Core/Cache/CacheableHelper.php b/core/lib/Drupal/Core/Cache/CacheableHelper.php
index be1f402..88cc9af 100644
--- a/core/lib/Drupal/Core/Cache/CacheableHelper.php
+++ b/core/lib/Drupal/Core/Cache/CacheableHelper.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\Core\Cache;
 
+use Drupal\Core\Database\Query\SelectInterface;
+
 /**
  * A helper class that contains methods that could be useful to any object using
  * the Drupal Cache API.
@@ -24,7 +26,7 @@ class CacheableHelper {
    * @return string
    *   A hash of the query arguments.
    */
-  function keyFromQuery($query) {
+  function keyFromQuery(SelectInterface $query) {
     $query->preExecute();
     $keys = array((string) $query, $query->getArguments());
     return hash('sha256', serialize($keys));
@@ -50,7 +52,7 @@ function addCacheContextsToKeys($keys) {
    * Provides the string representaton of a cache context.
    *
    * @todo Document this properly once the input arguments are decided on,
-   * assuming the reuse of existing cache constants is temporary.
+   *   assuming the reuse of existing cache constants is temporary.
    *
    * @return string
    *   The string representaton of a cache context.
diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Block/AggregatorFeedBlock.php b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Block/AggregatorFeedBlock.php
index 79ea257..4547527 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Block/AggregatorFeedBlock.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Block/AggregatorFeedBlock.php
@@ -79,7 +79,7 @@ public static function create(ContainerInterface $container, array $configuratio
    */
   public function defaultConfiguration() {
     // By default, the block will contain 10 feed items.
-    return parent::defaultConfiguration() + array(
+    return array(
       'block_count' => 10,
       'feed' => NULL,
     );
diff --git a/core/modules/block/custom_block/lib/Drupal/custom_block/Plugin/Block/CustomBlockBlock.php b/core/modules/block/custom_block/lib/Drupal/custom_block/Plugin/Block/CustomBlockBlock.php
index c6df55d..fe7f461 100644
--- a/core/modules/block/custom_block/lib/Drupal/custom_block/Plugin/Block/CustomBlockBlock.php
+++ b/core/modules/block/custom_block/lib/Drupal/custom_block/Plugin/Block/CustomBlockBlock.php
@@ -89,7 +89,7 @@ public static function create(ContainerInterface $container, array $configuratio
    * {@inheritdoc}
    */
   public function defaultConfiguration() {
-    return parent::defaultConfiguration() + array(
+    return array(
       'status' => TRUE,
       'info' => '',
       'view_mode' => 'full',
diff --git a/core/modules/block/lib/Drupal/block/BlockBase.php b/core/modules/block/lib/Drupal/block/BlockBase.php
index 6e99c48..c5b2d4a 100644
--- a/core/modules/block/lib/Drupal/block/BlockBase.php
+++ b/core/modules/block/lib/Drupal/block/BlockBase.php
@@ -30,11 +30,7 @@
   public function __construct(array $configuration, $plugin_id, array $plugin_definition) {
     parent::__construct($configuration, $plugin_id, $plugin_definition);
 
-    $this->configuration += $this->defaultConfiguration() + array(
-      'label' => '',
-      'module' => $plugin_definition['module'],
-      'label_display' => BlockInterface::BLOCK_LABEL_VISIBLE,
-    );
+    $this->setConfiguration($configuration);
   }
 
   /**
@@ -48,14 +44,14 @@ public function getConfiguration() {
    * {@inheritdoc}
    */
   public function setConfiguration(array $configuration) {
-    $this->configuration = $configuration;
+    $this->configuration = $configuration + $this->baseConfigurationDefaults() + $this->defaultConfiguration();
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  public function defaultConfiguration() {
+  protected function baseConfigurationDefaults() {
     return array(
+      'label' => '',
+      'module' => $this->pluginDefinition['module'],
+      'label_display' => BlockInterface::BLOCK_LABEL_VISIBLE,
       'cache' => array(
         'max_age' => 0,
       ),
@@ -65,6 +61,13 @@ public function defaultConfiguration() {
   /**
    * {@inheritdoc}
    */
+  public function defaultConfiguration() {
+    return array();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public function setConfigurationValue($key, $value) {
     $this->configuration[$key] = $value;
   }
diff --git a/core/modules/block/tests/modules/block_test/lib/Drupal/block_test/Plugin/Block/TestBlockInstantiation.php b/core/modules/block/tests/modules/block_test/lib/Drupal/block_test/Plugin/Block/TestBlockInstantiation.php
index 2834393..85856a3 100644
--- a/core/modules/block/tests/modules/block_test/lib/Drupal/block_test/Plugin/Block/TestBlockInstantiation.php
+++ b/core/modules/block/tests/modules/block_test/lib/Drupal/block_test/Plugin/Block/TestBlockInstantiation.php
@@ -24,7 +24,7 @@ class TestBlockInstantiation extends BlockBase {
    * {@inheritdoc}
    */
   public function defaultConfiguration() {
-    return parent::defaultConfiguration() + array(
+    return array(
       'display_message' => 'no message set',
     );
   }
diff --git a/core/modules/book/lib/Drupal/book/Plugin/Block/BookNavigationBlock.php b/core/modules/book/lib/Drupal/book/Plugin/Block/BookNavigationBlock.php
index 1542a4d..e2cf674 100644
--- a/core/modules/book/lib/Drupal/book/Plugin/Block/BookNavigationBlock.php
+++ b/core/modules/book/lib/Drupal/book/Plugin/Block/BookNavigationBlock.php
@@ -64,7 +64,7 @@ public static function create(ContainerInterface $container, array $configuratio
    * {@inheritdoc}
    */
   public function defaultConfiguration() {
-    return parent::defaultConfiguration() + array(
+    return array(
       'block_mode' => "all pages",
     );
   }
diff --git a/core/modules/node/lib/Drupal/node/Plugin/Block/SyndicateBlock.php b/core/modules/node/lib/Drupal/node/Plugin/Block/SyndicateBlock.php
index 6fd195e..ebcacf6 100644
--- a/core/modules/node/lib/Drupal/node/Plugin/Block/SyndicateBlock.php
+++ b/core/modules/node/lib/Drupal/node/Plugin/Block/SyndicateBlock.php
@@ -25,7 +25,7 @@ class SyndicateBlock extends BlockBase {
    * {@inheritdoc}
    */
   public function defaultConfiguration() {
-    return parent::defaultConfiguration() + array(
+    return array(
       'block_count' => 10,
     );
   }
diff --git a/core/modules/statistics/lib/Drupal/statistics/Plugin/Block/StatisticsPopularBlock.php b/core/modules/statistics/lib/Drupal/statistics/Plugin/Block/StatisticsPopularBlock.php
index 256fd40..1a19761 100644
--- a/core/modules/statistics/lib/Drupal/statistics/Plugin/Block/StatisticsPopularBlock.php
+++ b/core/modules/statistics/lib/Drupal/statistics/Plugin/Block/StatisticsPopularBlock.php
@@ -45,7 +45,7 @@ class StatisticsPopularBlock extends BlockBase {
    * {@inheritdoc}
    */
   public function defaultConfiguration() {
-    return parent::defaultConfiguration() + array(
+    return array(
       'top_day_num' => 0,
       'top_all_num' => 0,
       'top_last_num' => 0
diff --git a/core/modules/system/lib/Drupal/system/Plugin/Block/SystemMenuBlock.php b/core/modules/system/lib/Drupal/system/Plugin/Block/SystemMenuBlock.php
index 8a5e372..7d91859 100644
--- a/core/modules/system/lib/Drupal/system/Plugin/Block/SystemMenuBlock.php
+++ b/core/modules/system/lib/Drupal/system/Plugin/Block/SystemMenuBlock.php
@@ -33,7 +33,6 @@ public function build() {
    * {@inheritdoc}
    */
   public function defaultConfiguration() {
-    $default_configuration = parent::defaultConfiguration();
     // Modify the default max age for menu blocks: modifications made to menus,
     // menu links and menu blocks will automatically invalidate corresponding
     // cache tags, therefor allowing us to cache menu blocks forever. This is
@@ -42,8 +41,7 @@ public function defaultConfiguration() {
     // 1) it is possible to set a different max age for individual blocks, since
     //    this is just the default value.
     // 2) modules can modify caching by implementing hook_block_view_alter()
-    $default_configuration['cache']['max_age'] = \Drupal\Core\Cache\Cache::PERMANENT;
-    return $default_configuration;
+    return array('cache' => array('max_age' => \Drupal\Core\Cache\Cache::PERMANENT));
   }
 
   /**
diff --git a/core/modules/views/lib/Drupal/views/Plugin/Block/ViewsBlock.php b/core/modules/views/lib/Drupal/views/Plugin/Block/ViewsBlock.php
index 2648919..422e495 100644
--- a/core/modules/views/lib/Drupal/views/Plugin/Block/ViewsBlock.php
+++ b/core/modules/views/lib/Drupal/views/Plugin/Block/ViewsBlock.php
@@ -61,7 +61,7 @@ public function getConfiguration() {
    * {@inheritdoc}
    */
   public function defaultConfiguration() {
-    $settings = parent::defaultConfiguration();
+    $settings = array();
 
     if ($this->displaySet) {
       $settings += $this->view->display_handler->blockSettings($settings);
diff --git a/core/modules/views/lib/Drupal/views/Plugin/Block/ViewsBlockBase.php b/core/modules/views/lib/Drupal/views/Plugin/Block/ViewsBlockBase.php
index ded2b0c..3c228d1 100644
--- a/core/modules/views/lib/Drupal/views/Plugin/Block/ViewsBlockBase.php
+++ b/core/modules/views/lib/Drupal/views/Plugin/Block/ViewsBlockBase.php
@@ -99,7 +99,7 @@ public function access(AccountInterface $account) {
    * {@inheritdoc}
    */
   public function defaultConfiguration() {
-    return parent::defaultConfiguration() + array('views_label' => '');
+    return array('views_label' => '');
   }
 
   /**