How do I update definers to enable MySQL replication?

Question

I am trying to create a MySQL replica in Cloud SQL, Google's managed MySQL service. However I have the following error which won't allow me to start replication:

 "kind": "sql#externalSyncSettingErrorList",
  "errors": [
    {
      "kind": "sql#externalSyncSettingError",
      "type": "UNSUPPORTED_DEFINER",
      "detail": "Definer user root@localhost not supported. Please update host to '%'."
    }
  ]

The docs suggest this as the solution:

Update the definer in the external databases, for example from root@localhost to root@%

I am quite new to MySQL and I don't know how to make this change. I have done some research and it seems definers are related to some action like view, event, or routine so I suppose the question becomes which actions do I need to update the definer for to enable replication?

I found the following snippet which I guess is something like what I will need:

  foreach view, event, trigger, routine as object
    foreach object with definer=old_user 
      ALTER object DEFINER=new_user

Thanks in advance.