GUI Elasticsearch Initial master nodes not doing anything

As per https://roadmap.ploi.io/items/716-elasticsearch-discoveryseed-hosts-null-added-to-elasticsearchyml#comment-1072, filling the "Initial master nodes" field in the Elasticsearch UI config doesn't add the cluster.initial_master_nodes parameter to the /etc/elasticsearch/elasticsearch.yml file. In fact, doesn't appear to do anything.

Please fix as this goes hand in hand with the "Network host" as once changing that (usually because you want to enable remote access), without the "Initial master nodes" the Elasticsearch service will not restart.