diff --git a/core/lib/Drupal/Component/DependencyInjection/Container.php b/core/lib/Drupal/Component/DependencyInjection/Container.php
index 6b0df79..bf74487 100644
--- a/core/lib/Drupal/Component/DependencyInjection/Container.php
+++ b/core/lib/Drupal/Component/DependencyInjection/Container.php
@@ -188,7 +188,7 @@ public function get($id, $invalid_behavior = ContainerInterface::EXCEPTION_ON_IN
         unset($this->services[$id]);
       }
 
-      if (self::EXCEPTION_ON_INVALID_REFERENCE !== $invalid_behavior) {
+      if (ContainerInterface::EXCEPTION_ON_INVALID_REFERENCE !== $invalid_behavior) {
         return;
       }
 
@@ -354,7 +354,7 @@ protected function createService(array $definition, $id) {
   /**
    * {@inheritdoc}
    */
-  public function set($id, $service, $scope = self::SCOPE_CONTAINER) {
+  public function set($id, $service, $scope = ContainerInterface::SCOPE_CONTAINER) {
     $this->services[$id] = $service;
   }
 
diff --git a/core/lib/Drupal/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumper.php b/core/lib/Drupal/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumper.php
index c0ec669..acaf796 100644
--- a/core/lib/Drupal/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumper.php
+++ b/core/lib/Drupal/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumper.php
@@ -69,7 +69,7 @@ public function getArray() {
     $definition['parameters'] = $this->getParameters();
     $definition['services'] = $this->getServiceDefinitions();
     $definition['frozen'] = $this->container->isFrozen();
-    $definition['machine_format'] = $this->getMachineFormat();
+    $definition['machine_format'] = $this->supportsMachineFormat();
     return $definition;
   }
 
@@ -515,7 +515,7 @@ protected function getExpressionCall($expression) {
    * @return bool
    *   TRUE if this supports machine-optimized format, FALSE otherwise.
    */
-  protected function getMachineFormat() {
+  protected function supportsMachineFormat() {
     return TRUE;
   }
 
diff --git a/core/lib/Drupal/Component/DependencyInjection/Dumper/PhpArrayDumper.php b/core/lib/Drupal/Component/DependencyInjection/Dumper/PhpArrayDumper.php
index 2f2f517..4932dd7 100644
--- a/core/lib/Drupal/Component/DependencyInjection/Dumper/PhpArrayDumper.php
+++ b/core/lib/Drupal/Component/DependencyInjection/Dumper/PhpArrayDumper.php
@@ -70,7 +70,7 @@ protected function getParameterCall($name) {
   /**
    * {@inheritdoc}
    */
-  protected function getMachineFormat() {
+  protected function supportsMachineFormat() {
     return FALSE;
   }
 
diff --git a/core/lib/Drupal/Component/DependencyInjection/composer.json b/core/lib/Drupal/Component/DependencyInjection/composer.json
new file mode 100644
index 0000000..7e5e666
--- /dev/null
+++ b/core/lib/Drupal/Component/DependencyInjection/composer.json
@@ -0,0 +1,18 @@
+{
+  "name": "drupal/core-dependency-injection",
+  "description": "Dependency Injection container optimized for Drupal's needs.",
+  "keywords": ["drupal", "dependency injection"],
+  "type": "library",
+  "homepage": "https://www.drupal.org/project/drupal",
+  "license": "GPL-2.0+",
+  "support": {
+    "issues": "https://www.drupal.org/project/issues/drupal",
+    "irc": "irc://irc.freenode.net/drupal-contribute",
+    "source": "https://www.drupal.org/project/drupal/git-instructions"
+  },
+  "autoload": {
+    "psr-4": {
+      "Drupal\\Component\\DependencyInjection\\": ""
+    }
+  }
+}
diff --git a/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php b/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php
index 3802e84..fff8364 100644
--- a/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php
+++ b/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php
@@ -882,6 +882,9 @@ protected function getMockContainerDefinition() {
     $services['synthetic'] = array(
       'synthetic' => TRUE,
     );
+    // The file could have been named as a .php file. The reason it is a .data
+    // file is that SimpleTest tries to load it. SimpleTest does not like such
+    // fixtures and hence we use a neutral name like .data.
     $services['container_test_file_service_test'] = array(
       'class' => '\stdClass',
       'file' => __DIR__ . '/Fixture/container_test_file_service_test_service_function.data',
diff --git a/core/tests/Drupal/Tests/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumperTest.php b/core/tests/Drupal/Tests/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumperTest.php
index 72af63e..b315403 100644
--- a/core/tests/Drupal/Tests/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumperTest.php
+++ b/core/tests/Drupal/Tests/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumperTest.php
@@ -63,7 +63,7 @@ public function setUp() {
      *
      * @covers ::dump
      * @covers ::getArray
-     * @covers ::getMachineFormat
+     * @covers ::supportsMachineFormat
      */
     public function testDumpForEmptyContainer() {
       $serialized_definition = $this->dumper->dump();