--- /dev/null
+<?php
+
+namespace Drupal\comment\Plugin\migrate\source\d7;
+
+use Drupal\migrate\Row;
+use Drupal\migrate_drupal\Plugin\migrate\source\d7\FieldableEntity;
+
+/**
+ * Provides Drupal 7 comment entity translation source plugin.
+ *
+ * @MigrateSource(
+ * id = "d7_comment_entity_translation",
+ * source_module = "entity_translation"
+ * )
+ */
+class CommentEntityTranslation extends FieldableEntity {
+
+ /**
+ * {@inheritdoc}
+ */
+ public function query() {
+ $query = $this->select('entity_translation', 'et')
+ ->fields('et')
+ ->fields('c', [
+ 'subject',
+ ])
+ ->condition('et.entity_type', 'comment')
+ ->condition('et.source', '', '<>');
+
+ $query->innerJoin('comment', 'c', 'c.cid = et.entity_id');
+ $query->innerJoin('node', 'n', 'n.nid = c.nid');
+
+ $query->addField('n', 'type', 'node_type');
+
+ $query->orderBy('et.created');
+
+ return $query;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function prepareRow(Row $row) {
+ $cid = $row->getSourceProperty('entity_id');
+ $language = $row->getSourceProperty('language');
+ $node_type = $row->getSourceProperty('node_type');
+ $comment_type = 'comment_node_' . $node_type;
+
+ // Get Field API field values.
+ foreach ($this->getFields('comment', $comment_type) as $field_name => $field) {
+ // Ensure we're using the right language if the entity is translatable.
+ $field_language = $field['translatable'] ? $language : NULL;
+ $row->setSourceProperty($field_name, $this->getFieldValues('comment', $field_name, $cid, NULL, $field_language));
+ }
+
+ // If the comment subject was replaced by a real field using the Drupal 7
+ // Title module, use the field value instead of the comment subject.
+ if ($this->moduleExists('title')) {
+ $subject_field = $row->getSourceProperty('subject_field');
+ if (isset($subject_field[0]['value'])) {
+ $row->setSourceProperty('subject', $subject_field[0]['value']);
+ }
+ }
+
+ return parent::prepareRow($row);
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function fields() {
+ return [
+ 'entity_type' => $this->t('The entity type this translation relates to'),
+ 'entity_id' => $this->t('The entity ID this translation relates to'),
+ 'revision_id' => $this->t('The entity revision ID this translation relates to'),
+ 'language' => $this->t('The target language for this translation.'),
+ 'source' => $this->t('The source language from which this translation was created.'),
+ 'uid' => $this->t('The author of this translation.'),
+ 'status' => $this->t('Boolean indicating whether the translation is published (visible to non-administrators).'),
+ 'translate' => $this->t('A boolean indicating whether this translation needs to be updated.'),
+ 'created' => $this->t('The Unix timestamp when the translation was created.'),
+ 'changed' => $this->t('The Unix timestamp when the translation was most recently saved.'),
+ 'subject' => $this->t('The comment title.'),
+ ];
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getIds() {
+ return [
+ 'entity_id' => [
+ 'type' => 'integer',
+ 'alias' => 'et',
+ ],
+ 'language' => [
+ 'type' => 'string',
+ 'alias' => 'et',
+ ],
+ ];
+ }
+
+}