* Provides an interface for a content entity type and its metadata.
*/
interface ContentEntityTypeInterface extends EntityTypeInterface {
+
+ /**
+ * Gets an array of entity revision metadata keys.
+ *
+ * @param bool $include_backwards_compatibility_field_names
+ * (optional and deprecated) Whether to provide the revision keys on a
+ * best-effort basis by looking at the base fields defined by the entity
+ * type. Note that this parameter will be removed in Drupal 9.0.0. Defaults
+ * to TRUE.
+ *
+ * @return array
+ * An array describing how the Field API can extract revision metadata
+ * information of this entity type:
+ * - revision_log_message: The name of the property that contains description
+ * of the changes that were made in the current revision.
+ * - revision_user: The name of the property that contains the user ID of
+ * the author of the current revision.
+ * - revision_created: The name of the property that contains the timestamp
+ * of the current revision.
+ */
+ public function getRevisionMetadataKeys($include_backwards_compatibility_field_names = TRUE);
+
+ /**
+ * Gets a specific entity revision metadata key.
+ *
+ * @param string $key
+ * The name of the entity revision metadata key to return.
+ *
+ * @return string|bool
+ * The entity revision metadata key, or FALSE if it does not exist.
+ *
+ * @see self::getRevisionMetadataKeys()
+ */
+ public function getRevisionMetadataKey($key);
+
+ /**
+ * Indicates if a given entity revision metadata key exists.
+ *
+ * @param string $key
+ * The name of the entity revision metadata key to check.
+ *
+ * @return bool
+ * TRUE if a given entity revision metadata key exists, FALSE otherwise.
+ */
+ public function hasRevisionMetadataKey($key);
+
}