UI and better (verbose) output for requirements sensor to ignore certain requirements

+++ b/src/Plugin/monitoring/SensorPlugin/CoreRequirementsSensorPlugin.php
@@ -38,17 +38,28 @@ class CoreRequirementsSensorPlugin extends SensorPluginBase {
-  public function runSensor(SensorResultInterface $result) {
-    $requirements = $this->getRequirements($this->sensorConfig->getSetting('module'));
+  public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
+    $form = parent::buildConfigurationForm($form, $form_state);

Can you add the new buildConfigurationForm() method below runSensor() ? This makes it harder to review.

+++ b/src/Plugin/monitoring/SensorPlugin/CoreRequirementsSensorPlugin.php
@@ -38,17 +38,28 @@ class CoreRequirementsSensorPlugin extends SensorPluginBase {
+      '#description' => t('Seperate the keys by a semicolan (;)'),

That thing is called semicolon, not colan :)

+++ b/src/Plugin/monitoring/SensorPlugin/CoreRequirementsSensorPlugin.php
@@ -38,17 +38,28 @@ class CoreRequirementsSensorPlugin extends SensorPluginBase {
+    if (!$this->sensorConfig->isNew()) {
+      $form['exclude_keys']['#default_value']  = implode(';', $this->sensorConfig->getSetting('exclude_keys'));
     }

Is the is new check necessary because it is not yet an array then? Maybe do an (array) cast instead?

+++ b/src/Plugin/monitoring/SensorPlugin/CoreRequirementsSensorPlugin.php
@@ -152,4 +163,17 @@ class CoreRequirementsSensorPlugin extends SensorPluginBase {
+
+  public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {

Missing docblock.

+++ b/src/Plugin/monitoring/SensorPlugin/CoreRequirementsSensorPlugin.php
@@ -152,4 +163,17 @@ class CoreRequirementsSensorPlugin extends SensorPluginBase {
+    foreach ($keys as $key) {
+      $key = trim($key);
+      $exclude_keys[$key] = $key;
+    }
+    $this->sensorConfig->settings['exclude_keys'] = $exclude_keys;

You can do this with $keys = array_map('trim', $keys), the current code also doesn't define $exclude_keys, so it could be undefined.

Also make sure that we are not saving an empty string here, "var_dump(explode(';', '')); returns an array with an empty string inside. So run array_filter() around it.

+++ b/src/Plugin/monitoring/SensorPlugin/CoreRequirementsSensorPlugin.php
@@ -38,11 +39,29 @@ class CoreRequirementsSensorPlugin extends SensorPluginBase {
+    $output['query'] = array(
+      '#type' => 'item',
+      '#title' => t('Excluded keys'),
+      '#markup' => '<pre>' . $excluded_keys . '</pre>',
+    );

Should be 'exclude_keys' instead of query.

Also, try making this a list instead now that we can return HTML and render arrays. #type item_list, and then #items as array of string.

+++ b/src/Plugin/monitoring/SensorPlugin/CoreRequirementsSensorPlugin.php
@@ -152,4 +191,14 @@ class CoreRequirementsSensorPlugin extends SensorPluginBase {
+    $keys = array_filter(explode("\n", $form_state->getValue(array('settings', 'exclude_keys'))));
+    $this->sensorConfig->settings['exclude_keys'] = $keys;

I think we still need the trim part here, between explode and array_filter.