--- /dev/null
+<?php
+
+/**
+ * This base plugin allows "http-equiv"-style meta tags, e.g. the content
+ * language meta tag, to be further customized.
+ */
+
+namespace Drupal\metatag\Plugin\metatag\Tag;
+
+abstract class MetaHttpEquivBase extends MetaNameBase {
+ /**
+ * Display the meta tag.
+ */
+ public function output() {
+ if (empty($this->value)) {
+ // If there is no value, we don't want a tag output.
+ $element = '';
+ }
+ else {
+ $element = [
+ '#tag' => 'meta',
+ '#attributes' => [
+ 'http-equiv' => $this->name,
+ 'content' => $this->value(),
+ ]
+ ];
+ }
+
+ return $element;
+ }
+}