diff --git a/core/lib/Drupal/Core/Form/FormBuilderInterface.php b/core/lib/Drupal/Core/Form/FormBuilderInterface.php
index ff7c6273128e1f54c5f7a9d83a1143c4c85fd62a..66d9da4c2f1e7a6b5ed896e8c097a24469b5fca5 100644
--- a/core/lib/Drupal/Core/Form/FormBuilderInterface.php
+++ b/core/lib/Drupal/Core/Form/FormBuilderInterface.php
@@ -149,7 +149,7 @@ public function rebuildForm($form_id, FormStateInterface &$form_state, $old_form
    *   The value must be one of the following:
    *   - The name of a class that implements \Drupal\Core\Form\FormInterface.
    *   - An instance of a class that implements \Drupal\Core\Form\FormInterface.
-   * @param $form_state
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
    *   The current state of the form. Most important is the
    *   $form_state->getValues() collection, a tree of data used to simulate the
    *   incoming \Drupal::request()->request information from a user's form
diff --git a/core/lib/Drupal/Core/Form/FormSubmitterInterface.php b/core/lib/Drupal/Core/Form/FormSubmitterInterface.php
index c3e0089b079189b4cdd66b8e89404e4542e039dc..9d078b3ca332e85cf0000b23b16065383abc74e7 100644
--- a/core/lib/Drupal/Core/Form/FormSubmitterInterface.php
+++ b/core/lib/Drupal/Core/Form/FormSubmitterInterface.php
@@ -27,9 +27,9 @@ public function doSubmitForm(&$form, FormStateInterface &$form_state);
    * Button-specific handlers are checked first. If none exist, the function
    * falls back to form-level handlers.
    *
-   * @param $form
+   * @param array $form
    *   An associative array containing the structure of the form.
-   * @param $form_state
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
    *   The current state of the form. If the user submitted the form by clicking
    *   a button with custom handler functions defined, those handlers will be
    *   stored here.
diff --git a/core/lib/Drupal/Core/Form/form.api.php b/core/lib/Drupal/Core/Form/form.api.php
index 0502ea3239212fd918c0a55ac99244ac72b0d780..210e9f36ed54969303cb3f44b61eba7e98784dae 100644
--- a/core/lib/Drupal/Core/Form/form.api.php
+++ b/core/lib/Drupal/Core/Form/form.api.php
@@ -186,13 +186,13 @@ function hook_ajax_render_alter(array &$data) {
  * hook_form_FORM_ID_alter(). So, for each module, the more general hooks are
  * called first followed by the more specific.
  *
- * @param $form
+ * @param array $form
  *   Nested array of form elements that comprise the form.
- * @param $form_state
+ * @param \Drupal\Core\Form\FormStateInterface $form_state
  *   The current state of the form. The arguments that
  *   \Drupal::formBuilder()->getForm() was originally called with are available
  *   in the array $form_state->getBuildInfo()['args'].
- * @param $form_id
+ * @param string $form_id
  *   A string that is the unique ID of the form, set by
  *   Drupal\Core\Form\FormInterface::getFormId().
  *
@@ -235,13 +235,13 @@ function hook_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_stat
  * hook_form_FORM_ID_alter(). So, for each module, the more general hooks are
  * called first followed by the more specific.
  *
- * @param $form
+ * @param array $form
  *   Nested array of form elements that comprise the form.
- * @param $form_state
+ * @param \Drupal\Core\Form\FormStateInterface $form_state
  *   The current state of the form. The arguments that
  *   \Drupal::formBuilder()->getForm() was originally called with are available
  *   in the array $form_state->getBuildInfo()['args'].
- * @param $form_id
+ * @param string $form_id
  *   String representing the name of the form itself. Typically this is the
  *   name of the function that generated the form.
  *
@@ -293,11 +293,11 @@ function hook_form_FORM_ID_alter(&$form, \Drupal\Core\Form\FormStateInterface $f
  * hook_form_FORM_ID_alter(). So, for each module, the more general hooks are
  * called first followed by the more specific.
  *
- * @param $form
+ * @param array $form
  *   Nested array of form elements that comprise the form.
- * @param $form_state
+ * @param \Drupal\Core\Form\FormStateInterface $form_state
  *   The current state of the form.
- * @param $form_id
+ * @param string $form_id
  *   String representing the name of the form itself. Typically this is the
  *   name of the function that generated the form.
  *
diff --git a/core/lib/Drupal/Core/Render/Element/FormElementBase.php b/core/lib/Drupal/Core/Render/Element/FormElementBase.php
index 75da91227dc4cf80bf5458e3bbcffe6d23e45079..bce01e19558d7d6dc497dcd3f91ffa87eb403960 100644
--- a/core/lib/Drupal/Core/Render/Element/FormElementBase.php
+++ b/core/lib/Drupal/Core/Render/Element/FormElementBase.php
@@ -132,7 +132,7 @@ public static function processPattern(&$element, FormStateInterface $form_state,
    * @param $element
    *   An associative array containing the properties and children of the
    *   generic form element.
-   * @param $form_state
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
    *   The current state of the form.
    * @param array $complete_form
    *   The complete form structure.
diff --git a/core/lib/Drupal/Core/Render/theme.api.php b/core/lib/Drupal/Core/Render/theme.api.php
index a67c53299b4e75fc3247dfaf44acc535e3e7463d..fa447c20063018f00c6622743ea56abe9ff26d97 100644
--- a/core/lib/Drupal/Core/Render/theme.api.php
+++ b/core/lib/Drupal/Core/Render/theme.api.php
@@ -525,9 +525,9 @@
  * Note that the base theme's form alterations will be run before any sub-theme
  * alterations.
  *
- * @param $form
+ * @param array $form
  *   Nested array of form elements that comprise the form.
- * @param $form_state
+ * @param \Drupal\Core\Form\FormStateInterface $form_state
  *   The current state of the form.
  */
 function hook_form_system_theme_settings_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state) {
diff --git a/core/modules/field/field.api.php b/core/modules/field/field.api.php
index f8d72a26dbac7e45ddbc0a9945b93c338c4c35b9..b33aa3c282b65211f8ab492c94e6bea094ad61be 100644
--- a/core/modules/field/field.api.php
+++ b/core/modules/field/field.api.php
@@ -257,10 +257,10 @@ function hook_field_widget_single_element_WIDGET_TYPE_form_alter(array &$element
 /**
  * Alter the complete form for field widgets provided by other modules.
  *
- * @param $field_widget_complete_form
+ * @param array $field_widget_complete_form
  *   The field widget form element as constructed by
  *   \Drupal\Core\Field\WidgetBaseInterface::form().
- * @param $form_state
+ * @param \Drupal\Core\Form\FormStateInterface $form_state
  *   The current state of the form.
  * @param $context
  *   An associative array containing the following key-value pairs:
diff --git a/core/modules/media_library/src/Form/FileUploadForm.php b/core/modules/media_library/src/Form/FileUploadForm.php
index fd2bc14a419cb4fe1076d4068420e6fe3fdf40e3..e9e25f108fca6afae3ed647d274cda1e2d1b1370 100644
--- a/core/modules/media_library/src/Form/FileUploadForm.php
+++ b/core/modules/media_library/src/Form/FileUploadForm.php
@@ -276,7 +276,7 @@ protected function buildEntityFormElement(MediaInterface $media, array $form, Fo
    *   The entity form source field element.
    * @param \Drupal\Core\Form\FormStateInterface $form_state
    *   The current form state.
-   * @param $form
+   * @param array $form
    *   The complete form.
    *
    * @return array
diff --git a/core/modules/node/src/NodeForm.php b/core/modules/node/src/NodeForm.php
index bd71a44a3d945c7064d79d22ce590d923e731c75..31c97b3cb4c8ea889e4350fa2c261bca5c90a205 100644
--- a/core/modules/node/src/NodeForm.php
+++ b/core/modules/node/src/NodeForm.php
@@ -244,9 +244,9 @@ protected function actions(array $form, FormStateInterface $form_state) {
   /**
    * Form submission handler for the 'preview' action.
    *
-   * @param $form
+   * @param array $form
    *   An associative array containing the structure of the form.
-   * @param $form_state
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
    *   The current state of the form.
    */
   public function preview(array $form, FormStateInterface $form_state) {
diff --git a/core/modules/options/src/Plugin/Field/FieldType/ListItemBase.php b/core/modules/options/src/Plugin/Field/FieldType/ListItemBase.php
index 46af4ccd42cdcb71f23573661bf60a353e603bc0..47f1705481b1272b60a6a90848eb330f964386b0 100644
--- a/core/modules/options/src/Plugin/Field/FieldType/ListItemBase.php
+++ b/core/modules/options/src/Plugin/Field/FieldType/ListItemBase.php
@@ -339,7 +339,7 @@ abstract protected function allowedValuesDescription();
    * @param $element
    *   An associative array containing the properties and children of the
    *   generic form element.
-   * @param $form_state
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
    *   The current state of the form for the form this element belongs to.
    *
    * @see \Drupal\Core\Render\Element\FormElementBase::processPattern()
diff --git a/core/modules/system/tests/modules/theme_test/src/ThemeTestPreprocess.php b/core/modules/system/tests/modules/theme_test/src/ThemeTestPreprocess.php
index 211af09edd5418c86a9bece574723d8f91b2dc4e..5749af5778276f7f42a4354828ad134e8875bc42 100644
--- a/core/modules/system/tests/modules/theme_test/src/ThemeTestPreprocess.php
+++ b/core/modules/system/tests/modules/theme_test/src/ThemeTestPreprocess.php
@@ -12,7 +12,7 @@ class ThemeTestPreprocess {
   /**
    * Preprocess callback for testing preprocess callbacks.
    *
-   * @param $variables
+   * @param array $variables
    *   An associative array containing:
    *   - foo: Text for testing preprocess callback.
    */
diff --git a/core/modules/views/src/Plugin/views/HandlerBase.php b/core/modules/views/src/Plugin/views/HandlerBase.php
index 583efd832c4c2bb84031734e7d0f3cbb47557773..f34d08737036c0d7fbe87ac524af9a8676a49caf 100644
--- a/core/modules/views/src/Plugin/views/HandlerBase.php
+++ b/core/modules/views/src/Plugin/views/HandlerBase.php
@@ -334,6 +334,12 @@ public function usesGroupBy() {
 
   /**
    * Provide a form for aggregation settings.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function buildGroupByForm(&$form, FormStateInterface $form_state) {
     $display_id = $form_state->get('display_id');
@@ -361,6 +367,12 @@ public function buildGroupByForm(&$form, FormStateInterface $form_state) {
    * Perform any necessary changes to the form values prior to storage.
    *
    * There is no need for this function to actually store the data.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function submitGroupByForm(&$form, FormStateInterface $form_state) {
     $form_state->get('handler')->options['group_type'] = $form_state->getValue(['options', 'group_type']);
@@ -383,11 +395,22 @@ public function defineExtraOptions(&$option) {}
 
   /**
    * Provide a form for setting options.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function buildExtraOptionsForm(&$form, FormStateInterface $form_state) {}
 
   /**
    * Validate the options form.
+   *
+   * @param array $form
+   *   Associative array containing the structure of the form.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function validateExtraOptionsForm($form, FormStateInterface $form_state) {}
 
@@ -395,6 +418,11 @@ public function validateExtraOptionsForm($form, FormStateInterface $form_state)
    * Perform any necessary changes to the form values prior to storage.
    *
    * There is no need for this function to actually store the data.
+   *
+   * @param array $form
+   *   Associative array containing the structure of the form.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function submitExtraOptionsForm($form, FormStateInterface $form_state) {}
 
@@ -417,26 +445,55 @@ public function exposedInfo() {}
 
   /**
    * Render our chunk of the exposed handler form when selecting.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function buildExposedForm(&$form, FormStateInterface $form_state) {}
 
   /**
    * Validate the exposed handler form.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function validateExposed(&$form, FormStateInterface $form_state) {}
 
   /**
    * Submit the exposed handler form.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function submitExposed(&$form, FormStateInterface $form_state) {}
 
   /**
    * Form for exposed handler options.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function buildExposeForm(&$form, FormStateInterface $form_state) {}
 
   /**
    * Validate the options form.
+   *
+   * @param array $form
+   *   Associative array containing the structure of the form.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function validateExposeForm($form, FormStateInterface $form_state) {}
 
@@ -444,16 +501,33 @@ public function validateExposeForm($form, FormStateInterface $form_state) {}
    * Perform any necessary changes to the form exposes prior to storage.
    *
    * There is no need for this function to actually store the data.
+   *
+   * @param array $form
+   *   Associative array containing the structure of the form.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function submitExposeForm($form, FormStateInterface $form_state) {}
 
   /**
    * Shortcut to display the expose/hide button.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function showExposeButton(&$form, FormStateInterface $form_state) {}
 
   /**
    * Shortcut to display the exposed options form.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function showExposeForm(&$form, FormStateInterface $form_state) {
     if (empty($this->options['exposed'])) {
@@ -770,6 +844,11 @@ public static function breakString($str, $force_int = FALSE) {
 
   /**
    * Displays the Expose form.
+   *
+   * @param array $form
+   *   Associative array containing the structure of the form.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function displayExposedForm($form, FormStateInterface $form_state) {
     $item = &$this->options;
diff --git a/core/modules/views/src/Plugin/views/ViewsHandlerInterface.php b/core/modules/views/src/Plugin/views/ViewsHandlerInterface.php
index 8a61d56548c3a99756f072784e7f24e9640fed82..cf060c0aa6c5510a6c2204951805442b6f577466 100644
--- a/core/modules/views/src/Plugin/views/ViewsHandlerInterface.php
+++ b/core/modules/views/src/Plugin/views/ViewsHandlerInterface.php
@@ -109,6 +109,11 @@ public function postExecute(&$values);
 
   /**
    * Shortcut to display the exposed options form.
+   *
+   * @param array $form
+   *   The form array to alter, passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function showExposeForm(&$form, FormStateInterface $form_state);
 
diff --git a/core/modules/views/src/Plugin/views/ViewsPluginInterface.php b/core/modules/views/src/Plugin/views/ViewsPluginInterface.php
index 4304be07d8dbfe0d01aa9268ad30daffb7dd9450..7caf2faab0bf3f55ccae605aa602e9219871f508 100644
--- a/core/modules/views/src/Plugin/views/ViewsPluginInterface.php
+++ b/core/modules/views/src/Plugin/views/ViewsPluginInterface.php
@@ -43,6 +43,12 @@ public function filterByDefinedOptions(array &$storage);
 
   /**
    * Validate the options form.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function validateOptionsForm(&$form, FormStateInterface $form_state);
 
@@ -82,6 +88,12 @@ public function init(ViewExecutable $view, DisplayPluginBase $display, ?array &$
 
   /**
    * Handle any special handling on the validate form.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function submitOptionsForm(&$form, FormStateInterface $form_state);
 
diff --git a/core/modules/views/src/Plugin/views/filter/FilterPluginBase.php b/core/modules/views/src/Plugin/views/filter/FilterPluginBase.php
index f817f88fb137a5d00e095de7e452cd50ced3adf1..0515864e5927ead525b2083959cadf8faa660d82 100644
--- a/core/modules/views/src/Plugin/views/filter/FilterPluginBase.php
+++ b/core/modules/views/src/Plugin/views/filter/FilterPluginBase.php
@@ -242,6 +242,12 @@ public function isAGroup() {
    * If overridden, it is best to call through to the parent,
    * or to at least make sure all of the functions in this form
    * are called.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function buildOptionsForm(&$form, FormStateInterface $form_state) {
     parent::buildOptionsForm($form, $form_state);
@@ -283,6 +289,12 @@ public function buildOptionsForm(&$form, FormStateInterface $form_state) {
 
   /**
    * Simple validate handler.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function validateOptionsForm(&$form, FormStateInterface $form_state) {
     $this->operatorValidate($form, $form_state);
@@ -297,6 +309,12 @@ public function validateOptionsForm(&$form, FormStateInterface $form_state) {
 
   /**
    * Simple submit handler.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function submitOptionsForm(&$form, FormStateInterface $form_state) {
     // Do not store these values.
@@ -330,6 +348,12 @@ public function showOperatorForm(&$form, FormStateInterface $form_state) {
    * This may be overridden by child classes, and it must
    * define $form['operator'];
    *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
+   *
    * @see buildOptionsForm()
    */
   protected function operatorForm(&$form, FormStateInterface $form_state) {
@@ -355,6 +379,11 @@ public function operatorOptions() {
 
   /**
    * Validate the operator form.
+   *
+   * @param array $form
+   *   Associative array containing the structure of the form.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   protected function operatorValidate($form, FormStateInterface $form_state) {}
 
@@ -362,11 +391,22 @@ protected function operatorValidate($form, FormStateInterface $form_state) {}
    * Perform any necessary changes to the form values prior to storage.
    *
    * There is no need for this function to actually store the data.
+   *
+   * @param array $form
+   *   Associative array containing the structure of the form.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function operatorSubmit($form, FormStateInterface $form_state) {}
 
   /**
    * Shortcut to display the value form.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   protected function showValueForm(&$form, FormStateInterface $form_state) {
     $this->valueForm($form, $form_state);
@@ -382,6 +422,12 @@ protected function showValueForm(&$form, FormStateInterface $form_state) {
    * This should be overridden by all child classes and it must
    * define $form['value']
    *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
+   *
    * @see buildOptionsForm()
    */
   protected function valueForm(&$form, FormStateInterface $form_state) {
@@ -390,6 +436,11 @@ protected function valueForm(&$form, FormStateInterface $form_state) {
 
   /**
    * Validate the options form.
+   *
+   * @param array $form
+   *   Associative array containing the structure of the form.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   protected function valueValidate($form, FormStateInterface $form_state) {}
 
@@ -397,11 +448,22 @@ protected function valueValidate($form, FormStateInterface $form_state) {}
    * Perform any necessary changes to the form values prior to storage.
    *
    * There is no need for this function to actually store the data.
+   *
+   * @param array $form
+   *   Associative array containing the structure of the form.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   protected function valueSubmit($form, FormStateInterface $form_state) {}
 
   /**
    * Shortcut to display the exposed options form.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function showBuildGroupForm(&$form, FormStateInterface $form_state) {
     if (empty($this->options['is_grouped'])) {
@@ -425,6 +487,12 @@ public function showBuildGroupForm(&$form, FormStateInterface $form_state) {
 
   /**
    * Shortcut to display the build_group/hide button.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   protected function showBuildGroupButton(&$form, FormStateInterface $form_state) {
 
@@ -502,6 +570,12 @@ public function buildGroupForm($form, FormStateInterface $form_state) {
 
   /**
    * Shortcut to display the expose/hide button.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function showExposeButton(&$form, FormStateInterface $form_state) {
     $form['expose_button'] = [
@@ -552,6 +626,12 @@ public function showExposeButton(&$form, FormStateInterface $form_state) {
   /**
    * Options form subform for exposed filter options.
    *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
+   *
    * @see buildOptionsForm()
    */
   public function buildExposeForm(&$form, FormStateInterface $form_state) {
@@ -945,6 +1025,12 @@ public function groupForm(&$form, FormStateInterface $form_state) {
    * Render our chunk of the exposed filter form when selecting.
    *
    * You can override this if it doesn't do what you expect.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   public function buildExposedForm(&$form, FormStateInterface $form_state) {
     if (empty($this->options['exposed'])) {
@@ -1041,6 +1127,12 @@ protected function buildValueWrapper(&$form, $wrapper_identifier) {
    * Build the form to let users create the group of exposed filters.
    *
    * This form is displayed when users click on button 'Build group'.
+   *
+   * @param array $form
+   *   An alterable, associative array containing the structure of the form,
+   *   passed by reference.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
    */
   protected function buildExposedFiltersGroupForm(&$form, FormStateInterface $form_state) {
     if (empty($this->options['exposed']) || empty($this->options['is_grouped'])) {