diff --git a/drush/key.drush.inc b/drush/key.drush.inc
index fc26f3c..1154f0b 100644
--- a/drush/key.drush.inc
+++ b/drush/key.drush.inc
@@ -1,5 +1,10 @@
 <?php
 
+/**
+ * @file
+ * Drush 8 commands.
+ */
+
 /**
  * Implements hook_drush_help().
  */
diff --git a/drush/key_delete.drush.inc b/drush/key_delete.drush.inc
index b1dcef2..453df36 100644
--- a/drush/key_delete.drush.inc
+++ b/drush/key_delete.drush.inc
@@ -1,5 +1,10 @@
 <?php
 
+/**
+ * @file
+ * Delete a key.
+ */
+
 use Drush\Log\LogLevel;
 
 /**
diff --git a/drush/key_list.drush.inc b/drush/key_list.drush.inc
index 05eb5e8..401db5e 100644
--- a/drush/key_list.drush.inc
+++ b/drush/key_list.drush.inc
@@ -1,5 +1,10 @@
 <?php
 
+/**
+ * @file
+ * Display a list of available keys.
+ */
+
 /**
  * Get a list of available keys.
  */
diff --git a/drush/key_provider_list.drush.inc b/drush/key_provider_list.drush.inc
index c9b7447..dc0b315 100644
--- a/drush/key_provider_list.drush.inc
+++ b/drush/key_provider_list.drush.inc
@@ -1,5 +1,10 @@
 <?php
 
+/**
+ * @file
+ * Display a list of available key providers.
+ */
+
 /**
  * Get a list of available key providers.
  */
diff --git a/drush/key_save.drush.inc b/drush/key_save.drush.inc
index 25e4151..a89a092 100644
--- a/drush/key_save.drush.inc
+++ b/drush/key_save.drush.inc
@@ -1,5 +1,10 @@
 <?php
 
+/**
+ * @file
+ * Save a key.
+ */
+
 use Drupal\Component\Serialization\Json;
 use Drush\Log\LogLevel;
 
diff --git a/drush/key_type_list.drush.inc b/drush/key_type_list.drush.inc
index 8075a02..c3dcfc7 100644
--- a/drush/key_type_list.drush.inc
+++ b/drush/key_type_list.drush.inc
@@ -1,5 +1,10 @@
 <?php
 
+/**
+ * @file
+ * Display a list of available key types.
+ */
+
 /**
  * Get a list of available key types.
  */
diff --git a/drush/key_value_get.drush.inc b/drush/key_value_get.drush.inc
index 6b9c728..2398b74 100644
--- a/drush/key_value_get.drush.inc
+++ b/drush/key_value_get.drush.inc
@@ -1,5 +1,10 @@
 <?php
 
+/**
+ * @file
+ * Get a key value.
+ */
+
 /**
  * Get a key value.
  *
diff --git a/key.api.php b/key.api.php
index ad0056f..3271c6a 100644
--- a/key.api.php
+++ b/key.api.php
@@ -1,4 +1,5 @@
 <?php
+
 /**
  * @file
  * Hooks specific to the Key module.
diff --git a/src/Annotation/KeyInput.php b/src/Annotation/KeyInput.php
index b43458a..965f787 100644
--- a/src/Annotation/KeyInput.php
+++ b/src/Annotation/KeyInput.php
@@ -21,18 +21,18 @@ class KeyInput extends Plugin {
   /**
    * The human-readable name of the key input.
    *
-   * @ingroup plugin_translatable
-   *
    * @var \Drupal\Core\Annotation\Translation
+   *
+   * @ingroup plugin_translatable
    */
   public $label;
 
   /**
    * The description of the key input.
    *
-   * @ingroup plugin_translatable
-   *
    * @var \Drupal\Core\Annotation\Translation
+   *
+   * @ingroup plugin_translatable
    */
   public $description;
 
diff --git a/src/Annotation/KeyProvider.php b/src/Annotation/KeyProvider.php
index 5b0025b..5ea23f2 100644
--- a/src/Annotation/KeyProvider.php
+++ b/src/Annotation/KeyProvider.php
@@ -21,18 +21,18 @@ class KeyProvider extends Plugin {
   /**
    * The human-readable name of the key provider.
    *
-   * @ingroup plugin_translatable
-   *
    * @var \Drupal\Core\Annotation\Translation
+   *
+   * @ingroup plugin_translatable
    */
   public $label;
 
   /**
    * The description of the key provider.
    *
-   * @ingroup plugin_translatable
-   *
    * @var \Drupal\Core\Annotation\Translation
+   *
+   * @ingroup plugin_translatable
    */
   public $description;
 
diff --git a/src/Annotation/KeyType.php b/src/Annotation/KeyType.php
index fd9f90f..a6743c1 100644
--- a/src/Annotation/KeyType.php
+++ b/src/Annotation/KeyType.php
@@ -3,7 +3,6 @@
 namespace Drupal\key\Annotation;
 
 use Drupal\Component\Annotation\Plugin;
-use Drupal\Core\Annotation\Translation;
 
 /**
  * Defines a key type annotation object.
@@ -22,18 +21,18 @@ class KeyType extends Plugin {
   /**
    * The human-readable name of the key type.
    *
-   * @ingroup plugin_translatable
-   *
    * @var \Drupal\Core\Annotation\Translation
+   *
+   * @ingroup plugin_translatable
    */
   public $label;
 
   /**
    * The description of the key type.
    *
-   * @ingroup plugin_translatable
-   *
    * @var \Drupal\Core\Annotation\Translation
+   *
+   * @ingroup plugin_translatable
    */
   public $description;
 
@@ -82,7 +81,7 @@ class KeyType extends Plugin {
    */
   public $multivalue = [
     'enabled' => FALSE,
-    'fields' => []
+    'fields' => [],
   ];
 
 }
diff --git a/src/Commands/KeyCommands.php b/src/Commands/KeyCommands.php
index 3d2186f..f3bc551 100644
--- a/src/Commands/KeyCommands.php
+++ b/src/Commands/KeyCommands.php
@@ -1,18 +1,18 @@
 <?php
+
 namespace Drupal\key\Commands;
 
 use Consolidation\OutputFormatters\StructuredData\RowsOfFields;
 use Drupal\Component\Serialization\Json;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Logger\LoggerChannelFactoryInterface;
-use Drupal\key\Entity\Key;
 use Drupal\key\KeyRepositoryInterface;
 use Drupal\key\Plugin\KeyPluginManager;
 use Drush\Commands\DrushCommands;
 use Drush\Utils\StringUtils;
 
 /**
- * Class KeyCommands
+ * Class KeyCommands.
  *
  * @package Drupal\key\Commands
  */
@@ -53,6 +53,9 @@ class KeyCommands extends DrushCommands {
    */
   protected $keyProviderPluginManager;
 
+  /**
+   * Constructs a new KeyCommands drush command.
+   */
   public function __construct(
     KeyRepositoryInterface $repository,
     LoggerChannelFactoryInterface $logger,
@@ -70,9 +73,16 @@ class KeyCommands extends DrushCommands {
   /**
    * Save a key.
    *
+   * @param string $id
+   *   The ID (machine name) of the key to save.
+   * @param string $key_value
+   *   A key value to save. May or may not be allowed or required, depending on
+   *   the key provider.
+   * @param array $options
+   *   Options array.
+   *
    * @command key:save
-   * @param string $id The ID (machine name) of the key to save.
-   * @param string $key_value A key value to save. May or may not be allowed or required, depending on the key provider
+   *
    * @option label The human-readable label of the key.
    * @option description A short description of the key.
    * @option key-type The key type. To see a list of available key types, use `drush key-type-list`.
@@ -82,7 +92,8 @@ class KeyCommands extends DrushCommands {
    * @option key-input The key input method.
    * @option key-input-settings Settings specific to the defined key input, in JSON format.
    * @usage drush key-save secret_password 'pA$$w0rd' --label="Secret password" --key-type=authentication --key-provider=config --key-input=text_field
-   *   Define a key for a password to use for authentication using the Configuration key provider.
+   *   Define a key for a password to use for authentication using the
+   *   Configuration key provider.
    * @usage drush key-save encryption_key --label="Encryption key" --key-type=encryption --key-type-settings='{"key_size":256}' --key-provider=file --key-provider-settings='{"file_location":"private://keys/encryption.key", "base64_encoded":true}' --key-input=none
    *   Define a key to use for encryption using the File key provider.
    * @aliases key-save
@@ -90,15 +101,15 @@ class KeyCommands extends DrushCommands {
   public function save(
     $id,
     $key_value = NULL,
-    $options = [
-      'label' => null,
-      'description' => null,
-      'key-type' => null,
-      'key-type-settings' => null,
-      'key-provider' => null,
-      'key-provider-settings' => null,
-      'key-input' => null,
-      'key-input-settings' => null,
+    array $options = [
+      'label' => NULL,
+      'description' => NULL,
+      'key-type' => NULL,
+      'key-type-settings' => NULL,
+      'key-provider' => NULL,
+      'key-provider-settings' => NULL,
+      'key-input' => NULL,
+      'key-input-settings' => NULL,
     ]
   ) {
     $values = [];
@@ -177,12 +188,17 @@ class KeyCommands extends DrushCommands {
   /**
    * Delete a key.
    *
+   * @param string $id
+   *   The ID (machine name) of the key to delete.
+   * @param array $options
+   *   Options array.
+   *
    * @command key:delete
-   * @param string $id The ID (machine name) of the key to delete.
+   *
    * @aliases key-delete
    * @format table
    */
-  public function delete($id, $options = []) {
+  public function delete($id, array $options = []) {
     // Look for a key with the specified ID. If one does not exist, set an
     // error and abort.
     /* @var $key \Drupal\key\Entity\Key */
@@ -195,7 +211,7 @@ class KeyCommands extends DrushCommands {
     $this->logger->warning('Be extremely careful when deleting a key! It may result in losing access to a service or making encrypted data unreadable.');
     $this->output->writeln(dt('The following key will be deleted: !id', ['!id' => $id]));
     if (!$this->io()->confirm(dt('Do you want to continue?'))) {
-      // Removing drush_user_abort(), no current implemenation of that
+      // Removing drush_user_abort(), no current implemenation of that.
       return;
     }
 
@@ -216,13 +232,16 @@ class KeyCommands extends DrushCommands {
   /**
    * Display a list of available keys.
    *
+   * @param array $options
+   *   Options array.
+   *
    * @command key:list
    * @option key-type An optional, comma-delimited list of key types. To see a list of available key types, use `drush key-type-list`.
    * @option key-provider An optional, comma-delimited list of key providers. To see a list of available key providers, use `drush key-provider-list`.
    * @aliases key-list
    * @format table
    */
-  public function keyList($options = ['key-type' => null, 'key-provider' => null]) {
+  public function keyList(array $options = ['key-type' => NULL, 'key-provider' => NULL]) {
     $result = [];
 
     /* @var $key \Drupal\key\Entity\Key */
@@ -268,7 +287,7 @@ class KeyCommands extends DrushCommands {
    * @aliases key-type-list
    * @format table
    */
-  public function typeList($options = ['group' => null]) {
+  public function typeList($options = ['group' => NULL]) {
     $result = [];
 
     $group = $options['group'];
@@ -295,7 +314,7 @@ class KeyCommands extends DrushCommands {
    * @aliases key-provider-list
    * @format table
    */
-  public function providerList($options = ['storage-method' => null]) {
+  public function providerList($options = ['storage-method' => NULL]) {
     $result = [];
 
     $storage_method = $options['storage-method'];
@@ -317,13 +336,18 @@ class KeyCommands extends DrushCommands {
   /**
    * Display a list of available key providers.
    *
+   * @param string $id
+   *   The ID (machine name) of the key whose value should be retrieved.
+   * @param array $options
+   *   Options array.
+   *
    * @command key:value-get
-   * @param string $id The ID (machine name) of the key whose value should be retrieved.
+   *
    * @option base64 Base64-encode the key value. This is useful in the case of binary encryption keys that would otherwise not be displayed in a readable way.
    * @aliases key-value-get, key-value
    * @format table
    */
-  public function valueGet($id, $options = ['base64' => null]) {
+  public function valueGet($id, array $options = ['base64' => NULL]) {
     $result = [];
     // Look for a key with the specified ID. If one does not exist, set an
     // error and abort.
@@ -343,7 +367,7 @@ class KeyCommands extends DrushCommands {
     }
 
     $row = [];
-    $row ['Key value'] = $key_value;
+    $row['Key value'] = $key_value;
     $result[] = $row;
 
     return new RowsOfFields($result);
@@ -387,5 +411,4 @@ class KeyCommands extends DrushCommands {
     ];
   }
 
-
 }
diff --git a/src/Controller/KeyConfigOverrideListBuilder.php b/src/Controller/KeyConfigOverrideListBuilder.php
index 78b1d20..bd9d8b2 100644
--- a/src/Controller/KeyConfigOverrideListBuilder.php
+++ b/src/Controller/KeyConfigOverrideListBuilder.php
@@ -29,14 +29,14 @@ class KeyConfigOverrideListBuilder extends ConfigEntityListBuilder {
   /**
    * The configuration manager.
    *
-   * @var \Drupal\Core\Config\ConfigManagerInterface;
+   * @var \Drupal\Core\Config\ConfigManagerInterface
    */
   protected $configManager;
 
   /**
    * The key repository.
    *
-   * @var \Drupal\key\KeyRepositoryInterface;
+   * @var \Drupal\key\KeyRepositoryInterface
    */
   protected $keyRepository;
 
diff --git a/src/Controller/KeyListBuilder.php b/src/Controller/KeyListBuilder.php
index 1fce464..40ae599 100644
--- a/src/Controller/KeyListBuilder.php
+++ b/src/Controller/KeyListBuilder.php
@@ -25,6 +25,8 @@ class KeyListBuilder extends ConfigEntityListBuilder {
   protected $entityTypeManager;
 
   /**
+   * Overrides.
+   *
    * @var array
    */
   protected $overrides;
@@ -122,7 +124,6 @@ class KeyListBuilder extends ConfigEntityListBuilder {
     return $build;
   }
 
-
   /**
    * Get any overrides associated with a key.
    *
diff --git a/src/Element/KeySelect.php b/src/Element/KeySelect.php
index eb7a1a2..b0f0f21 100644
--- a/src/Element/KeySelect.php
+++ b/src/Element/KeySelect.php
@@ -52,7 +52,7 @@ class KeySelect extends Select {
    * @return array
    *   The processed element.
    */
-  public static function processKeySelect(&$element, FormStateInterface $form_state, &$complete_form) {
+  public static function processKeySelect(array &$element, FormStateInterface $form_state, array &$complete_form) {
     // Get the list of available keys and define the options.
     $options = \Drupal::service('key.repository')->getKeyNamesAsOptions($element['#key_filters']);
     $element['#options'] = $options;
diff --git a/src/Entity/Key.php b/src/Entity/Key.php
index b4713a4..323efec 100644
--- a/src/Entity/Key.php
+++ b/src/Entity/Key.php
@@ -124,7 +124,7 @@ class Key extends ConfigEntityBase implements KeyInterface, EntityWithPluginColl
   /**
    * The key value.
    *
-   * @var string|NULL
+   * @var string|null
    */
   protected $keyValue = NULL;
 
diff --git a/src/Exception/KeyException.php b/src/Exception/KeyException.php
index 7dc1e9c..bfc1971 100644
--- a/src/Exception/KeyException.php
+++ b/src/Exception/KeyException.php
@@ -5,4 +5,4 @@ namespace Drupal\key\Exception;
 /**
  * Defines a generic exception for Key.
  */
-class KeyException extends \Exception { }
+class KeyException extends \Exception {}
diff --git a/src/Exception/KeyValueNotDeletedException.php b/src/Exception/KeyValueNotDeletedException.php
index c376189..8d7b917 100644
--- a/src/Exception/KeyValueNotDeletedException.php
+++ b/src/Exception/KeyValueNotDeletedException.php
@@ -5,4 +5,4 @@ namespace Drupal\key\Exception;
 /**
  * Defines an exception for when a key value fails to be deleted.
  */
-class KeyValueNotDeletedException extends KeyException { }
+class KeyValueNotDeletedException extends KeyException {}
diff --git a/src/Exception/KeyValueNotRetrievedException.php b/src/Exception/KeyValueNotRetrievedException.php
index 7ae4c56..36ec519 100644
--- a/src/Exception/KeyValueNotRetrievedException.php
+++ b/src/Exception/KeyValueNotRetrievedException.php
@@ -5,4 +5,4 @@ namespace Drupal\key\Exception;
 /**
  * Defines an exception for when a key value fails to be retrieved.
  */
-class KeyValueNotRetrievedException extends KeyException { }
+class KeyValueNotRetrievedException extends KeyException {}
diff --git a/src/Exception/KeyValueNotSetException.php b/src/Exception/KeyValueNotSetException.php
index ad1582a..8d4799c 100644
--- a/src/Exception/KeyValueNotSetException.php
+++ b/src/Exception/KeyValueNotSetException.php
@@ -5,4 +5,4 @@ namespace Drupal\key\Exception;
 /**
  * Defines an exception for when a key value fails to be set.
  */
-class KeyValueNotSetException extends KeyException { }
+class KeyValueNotSetException extends KeyException {}
diff --git a/src/Form/KeyConfigOverrideAddForm.php b/src/Form/KeyConfigOverrideAddForm.php
index c2b517c..249c7c2 100644
--- a/src/Form/KeyConfigOverrideAddForm.php
+++ b/src/Form/KeyConfigOverrideAddForm.php
@@ -13,6 +13,9 @@ use Drupal\Core\StringTranslation\TranslatableMarkup;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\HttpFoundation\RequestStack;
 
+/**
+ * KeyConfigOverrideAddForm class.
+ */
 class KeyConfigOverrideAddForm extends EntityForm {
 
   /**
@@ -64,6 +67,10 @@ class KeyConfigOverrideAddForm extends EntityForm {
    *   The entity manager.
    * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
    *   The config factory.
+   * @param \Drupal\Core\Config\StorageInterface $config_storage
+   *   The config storage.
+   * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
+   *   The current request stack.
    */
   public function __construct(EntityTypeManagerInterface $entity_type_manager, ConfigFactoryInterface $config_factory, StorageInterface $config_storage, RequestStack $request_stack) {
     $this->entityTypeManager = $entity_type_manager;
@@ -194,7 +201,7 @@ class KeyConfigOverrideAddForm extends EntityForm {
       $definitions = $this->getConfigEntityTypeDefinitions();
       $config_type = $form_state->getValue('config_type');
 
-      if (key_exists($config_type, $definitions)) {
+      if (array_key_exists($config_type, $definitions)) {
         $config_prefix = $definitions[$config_type]->getConfigPrefix();
       }
       else {
@@ -308,7 +315,7 @@ class KeyConfigOverrideAddForm extends EntityForm {
       $names = $this->configStorage->listAll();
       $names = array_combine($names, $names);
 
-      // Filter out any names that match a configuration entity prefix
+      // Filter out any names that match a configuration entity prefix.
       foreach ($names as $config_name) {
         foreach ($config_prefixes as $config_prefix) {
           if (strpos($config_name, $config_prefix) === 0) {
@@ -361,7 +368,7 @@ class KeyConfigOverrideAddForm extends EntityForm {
    * Define the list of configuration types to exclude.
    *
    * @return array
-   *  The configuration types to exclude.
+   *   The configuration types to exclude.
    */
   protected function excludedConfigTypes() {
     $exclude = [
@@ -374,7 +381,7 @@ class KeyConfigOverrideAddForm extends EntityForm {
   /**
    * Recursively create a flat array of configuration items.
    *
-   * @param $config_array
+   * @param array $config_array
    *   An array of configuration items.
    * @param string $prefix
    *   A prefix to add to nested items.
@@ -384,7 +391,7 @@ class KeyConfigOverrideAddForm extends EntityForm {
    * @return array
    *   The flattened array of configuration items.
    */
-  protected function flattenConfigItemList($config_array, $prefix = '', $level = 0) {
+  protected function flattenConfigItemList(array $config_array, $prefix = '', $level = 0) {
     $config_items = [];
 
     // Define items to ignore.
diff --git a/src/Form/KeyConfigOverrideDeleteForm.php b/src/Form/KeyConfigOverrideDeleteForm.php
index cb9d6d1..ba37614 100644
--- a/src/Form/KeyConfigOverrideDeleteForm.php
+++ b/src/Form/KeyConfigOverrideDeleteForm.php
@@ -3,13 +3,13 @@
 namespace Drupal\key\Form;
 
 use Drupal\Core\Entity\EntityDeleteForm;
-use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Url;
 
 /**
  * Builds the form to delete a Key.
  */
 class KeyConfigOverrideDeleteForm extends EntityDeleteForm {
+
   /**
    * {@inheritdoc}
    */
diff --git a/src/Form/KeyFormBase.php b/src/Form/KeyFormBase.php
index 0812b03..dc4a6ca 100644
--- a/src/Form/KeyFormBase.php
+++ b/src/Form/KeyFormBase.php
@@ -6,7 +6,6 @@ use Drupal\Core\Entity\EntityForm;
 use Drupal\Core\Config\Entity\ConfigEntityStorageInterface;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\key\Entity\Key;
-use Drupal\key\Exception\KeyValueNotSetException;
 use Drupal\key\Plugin\KeyPluginFormInterface;
 use Drupal\key\Plugin\KeyProviderSettableValueInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
@@ -26,7 +25,7 @@ abstract class KeyFormBase extends EntityForm {
   /**
    * The original key.
    *
-   * @var \Drupal\key\Entity\Key|NULL
+   * @var \Drupal\key\Entity\Key|null
    *   The original key entity or NULL if this is a new key.
    */
   protected $originalKey = NULL;
@@ -486,10 +485,10 @@ abstract class KeyFormBase extends EntityForm {
    *
    * @param string $type
    *   The plugin type ID.
-   * @param FormStateInterface $form_state
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
    *   The form state to copy values from.
    *
-   * @return FormStateInterface
+   * @return \Drupal\Core\Form\FormStateInterface
    *   A clone of the form state object with values from the plugin.
    */
   protected function createPluginFormState($type, FormStateInterface $form_state) {
diff --git a/src/KeyConfigOverrideInterface.php b/src/KeyConfigOverrideInterface.php
index fa370bd..3fca7bd 100644
--- a/src/KeyConfigOverrideInterface.php
+++ b/src/KeyConfigOverrideInterface.php
@@ -4,11 +4,14 @@ namespace Drupal\key;
 
 use Drupal\Core\Config\Entity\ConfigEntityInterface;
 
+/**
+ * KeyConfigOverrideInterface interface.
+ */
 interface KeyConfigOverrideInterface extends ConfigEntityInterface {
 
   /**
    * Gets the configuration type.
-   * 
+   *
    * @return string
    *   The configuration type.
    */
@@ -16,7 +19,7 @@ interface KeyConfigOverrideInterface extends ConfigEntityInterface {
 
   /**
    * Gets the configuration name.
-   * 
+   *
    * @return string
    *   The configuration name.
    */
diff --git a/src/KeyConfigOverrides.php b/src/KeyConfigOverrides.php
index 7bb89bf..3405b0c 100644
--- a/src/KeyConfigOverrides.php
+++ b/src/KeyConfigOverrides.php
@@ -15,21 +15,29 @@ use Drupal\Core\Config\StorageInterface;
 class KeyConfigOverrides implements ConfigFactoryOverrideInterface {
 
   /**
+   * Config factory.
+   *
    * @var \Drupal\Core\Config\ConfigFactoryInterface
    */
   protected $configFactory;
 
   /**
+   * Cache backend.
+   *
    * @var \Drupal\Core\Cache\CacheBackendInterface
    */
   protected $cacheBackend;
 
   /**
+   * Mapping.
+   *
    * @var array
    */
   protected $mapping;
 
   /**
+   * In override.
+   *
    * @var bool
    */
   protected $inOverride = FALSE;
@@ -71,7 +79,7 @@ class KeyConfigOverrides implements ConfigFactoryOverrideInterface {
     $overrides = [];
 
     foreach ($names as $name) {
-      if (!key_exists($name, $mapping)) {
+      if (!array_key_exists($name, $mapping)) {
         continue;
       }
 
diff --git a/src/KeyRepository.php b/src/KeyRepository.php
index 3dcb239..7ff4be2 100644
--- a/src/KeyRepository.php
+++ b/src/KeyRepository.php
@@ -118,7 +118,7 @@ class KeyRepository implements KeyRepositoryInterface {
   /**
    * {@inheritdoc}
    */
-  public function getKeyNamesAsOptions($filters = []) {
+  public function getKeyNamesAsOptions(array $filters = []) {
     $options = [];
     $keys = $this->getKeys();
 
@@ -127,12 +127,15 @@ class KeyRepository implements KeyRepositoryInterface {
         case 'type':
           $keys = array_intersect_key($this->getKeysByType($filter), $keys);
           break;
+
         case 'provider':
           $keys = array_intersect_key($this->getKeysByProvider($filter), $keys);
           break;
+
         case 'type_group':
           $keys = array_intersect_key($this->getKeysByTypeGroup($filter), $keys);
           break;
+
         case 'storage_method':
           $keys = array_intersect_key($this->getKeysByStorageMethod($filter), $keys);
           break;
diff --git a/src/KeyRepositoryInterface.php b/src/KeyRepositoryInterface.php
index ae19308..47551a3 100644
--- a/src/KeyRepositoryInterface.php
+++ b/src/KeyRepositoryInterface.php
@@ -84,9 +84,9 @@ interface KeyRepositoryInterface {
    * @param array $filters
    *   An array of filters to apply to the list of options.
    *
-   * @return array An array of key names, indexed by id.
+   * @return array
    *   An array of key names, indexed by id.
    */
-  public function getKeyNamesAsOptions($filters);
+  public function getKeyNamesAsOptions(array $filters);
 
 }
diff --git a/src/Plugin/KeyPluginCollection.php b/src/Plugin/KeyPluginCollection.php
index f93acfd..68499ec 100644
--- a/src/Plugin/KeyPluginCollection.php
+++ b/src/Plugin/KeyPluginCollection.php
@@ -9,16 +9,6 @@ use Drupal\Core\Plugin\DefaultSingleLazyPluginCollection;
  */
 class KeyPluginCollection extends DefaultSingleLazyPluginCollection {
 
-  /**
-   * {@inheritdoc}
-   *
-   * @return \Drupal\key\Plugin\KeyPluginInterface
-   *   A Key plugin instance.
-   */
-  public function &get($instance_id) {
-    return parent::get($instance_id);
-  }
-
   /**
    * {@inheritdoc}
    */
diff --git a/src/Plugin/KeyPluginInterface.php b/src/Plugin/KeyPluginInterface.php
index 7d8b35f..e2ba0c8 100644
--- a/src/Plugin/KeyPluginInterface.php
+++ b/src/Plugin/KeyPluginInterface.php
@@ -2,14 +2,15 @@
 
 namespace Drupal\key\Plugin;
 
-use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Component\Plugin\ConfigurableInterface;
+use Drupal\Component\Plugin\DependentPluginInterface;
 use Drupal\Component\Plugin\PluginInspectionInterface;
-use Drupal\Component\Plugin\ConfigurablePluginInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
 
 /**
  * Provides an interface for all Key plugins.
  */
-interface KeyPluginInterface extends ContainerFactoryPluginInterface, PluginInspectionInterface, ConfigurablePluginInterface {
+interface KeyPluginInterface extends ContainerFactoryPluginInterface, PluginInspectionInterface, ConfigurableInterface, DependentPluginInterface {
 
   /**
    * Returns the type of plugin.
diff --git a/src/Plugin/KeyType/AuthenticationMultivalueKeyType.php b/src/Plugin/KeyType/AuthenticationMultivalueKeyType.php
index 1aee697..7aa888a 100644
--- a/src/Plugin/KeyType/AuthenticationMultivalueKeyType.php
+++ b/src/Plugin/KeyType/AuthenticationMultivalueKeyType.php
@@ -4,7 +4,6 @@ namespace Drupal\key\Plugin\KeyType;
 
 use Drupal\Component\Serialization\Json;
 use Drupal\Core\Form\FormStateInterface;
-use Drupal\key\Plugin\KeyPluginFormInterface;
 use Drupal\key\Plugin\KeyTypeBase;
 use Drupal\key\Plugin\KeyTypeMultivalueInterface;
 
@@ -61,7 +60,7 @@ class AuthenticationMultivalueKeyType extends KeyTypeBase implements KeyTypeMult
     $definition = $this->getPluginDefinition();
     $fields = $definition['multivalue']['fields'];
 
-    foreach($fields as $id => $field) {
+    foreach ($fields as $id => $field) {
       if (!is_array($field)) {
         $field = ['label' => $field];
       }
@@ -70,7 +69,7 @@ class AuthenticationMultivalueKeyType extends KeyTypeBase implements KeyTypeMult
         continue;
       }
 
-      if (!isset ($value[$id])) {
+      if (!isset($value[$id])) {
         $form_state->setError($error_element, $this->t('The key value is missing the field %field.', ['%field' => $id]));
       }
       elseif (empty($value[$id])) {
diff --git a/src/Plugin/KeyType/EncryptionKeyType.php b/src/Plugin/KeyType/EncryptionKeyType.php
index 377c8fd..77a0d2a 100644
--- a/src/Plugin/KeyType/EncryptionKeyType.php
+++ b/src/Plugin/KeyType/EncryptionKeyType.php
@@ -62,8 +62,8 @@ class EncryptionKeyType extends KeyTypeBase implements KeyPluginFormInterface {
       '#title_display' => 'invisible',
       '#description' => $this->t('Enter a custom key size in bits.'),
       '#default_value' => $key_size_other_value,
-      '#maxlength'=> 20,
-      '#size'=> 20,
+      '#maxlength' => 20,
+      '#size' => 20,
       '#states' => [
         'visible' => [
           'select[name="key_type_settings[key_size]"]' => ['value' => 'other'],
diff --git a/src/Plugin/KeyTypeMultivalueInterface.php b/src/Plugin/KeyTypeMultivalueInterface.php
index e8bbe2e..2577f21 100644
--- a/src/Plugin/KeyTypeMultivalueInterface.php
+++ b/src/Plugin/KeyTypeMultivalueInterface.php
@@ -11,7 +11,7 @@ interface KeyTypeMultivalueInterface {
    * Serialize an array of key values into a string.
    *
    * @param array $array
-   *   An array of key values
+   *   An array of key values.
    *
    * @return string
    *   A serialized string of key values.
diff --git a/tests/assets/testkey.txt b/tests/assets/testkey.txt
index 3d2ad72..5406af6 100644
--- a/tests/assets/testkey.txt
+++ b/tests/assets/testkey.txt
@@ -2,4 +2,4 @@ abc def ghi jkl mno pqr stu vwx yz1@3$
 
 abc def ghi jkl mno pqr stu vwx yz5^7*
 
-abc def ghi jkl mno pqr stu vwx yz9)
\ No newline at end of file
+abc def ghi jkl mno pqr stu vwx yz9)
diff --git a/tests/src/Unit/Entity/KeyEntityTest.php b/tests/src/Unit/Entity/KeyEntityTest.php
index cd91205..6c2d768 100644
--- a/tests/src/Unit/Entity/KeyEntityTest.php
+++ b/tests/src/Unit/Entity/KeyEntityTest.php
@@ -15,34 +15,46 @@ use Drupal\Tests\key\Unit\KeyTestBase;
 class KeyEntityTest extends KeyTestBase {
 
   /**
+   * Key type manager.
+   *
    * @var \Drupal\key\Plugin\KeyPluginManager
    */
   protected $keyTypeManager;
 
   /**
+   * Key provider manager.
+   *
    * @var \Drupal\key\Plugin\KeyPluginManager
    */
   protected $keyProviderManager;
 
   /**
+   * Key plugin manager.
+   *
    * @var \Drupal\key\Plugin\KeyPluginManager
    */
   protected $keyInputManager;
 
   /**
-   * @var []
+   * Key type settings.
+   *
+   * @var array
    *   Key type settings to use for Authentication key type.
    */
   protected $key_type_settings;
 
   /**
-   * @var []
+   * Key provider settings.
+   *
+   * @var array
    *   Key provider settings to use for Configuration key provider.
    */
   protected $key_provider_settings;
 
   /**
-   * @var []
+   * Key input settings.
+   *
+   * @var array
    *   Key input settings to use for None key input.
    */
   protected $key_input_settings;
@@ -110,7 +122,11 @@ class KeyEntityTest extends KeyTestBase {
       ->method('getDefinitions')
       ->willReturn([
         ['id' => 'file', 'label' => 'File', 'storage_method' => 'file'],
-        ['id' => 'config', 'label' => 'Configuration', 'storage_method' => 'config'],
+        [
+          'id' => 'config',
+          'label' => 'Configuration',
+          'storage_method' => 'config',
+        ],
       ]);
     $this->keyProviderManager->expects($this->any())
       ->method('createInstance')
diff --git a/tests/src/Unit/KeyTestBase.php b/tests/src/Unit/KeyTestBase.php
index a5a400c..e984859 100644
--- a/tests/src/Unit/KeyTestBase.php
+++ b/tests/src/Unit/KeyTestBase.php
@@ -11,25 +11,33 @@ use Drupal\Tests\UnitTestCase;
 abstract class KeyTestBase extends UnitTestCase {
 
   /**
+   * Config.
+   *
    * @var \Drupal\Core\Config\ImmutableConfig
    */
   protected $config;
 
   /**
+   * Configuration storage.
+   *
    * @var \Drupal\Core\Config\Entity\ConfigEntityStorage
    */
   protected $configStorage;
 
   /**
+   * Entity type manager instance.
+   *
    * @var \Drupal\Core\Entity\EntityTypeManager
    */
   protected $entityTypeManager;
 
   /**
-   * @var \Drupal\Core\DependencyInjection\ContainerBuilder
+   * Container builder.
    *
    * This should be used sparingly by test cases to add to the container as
    * necessary for tests.
+   *
+   * @var \Drupal\Core\DependencyInjection\ContainerBuilder
    */
   protected $container;