Incompatible typing in seestar_event.erl

[srmerritt]

event() is opaque, and the exported functions change/1, ip/1, port/1, keyspace/1, table/1 are spec'd to require unexported type(s): topology_change_event(), status_change_event(), schema_change_event().

Here's an example error:

The call seestar_event:ip(E::seestar_event:event()) contains an opaque term as 1st argument when a structured term of type {'status_change','down' | 'undefined' | 'up','undefined' | {byte(),byte(),byte(),byte()} | {char(),char(),char(),char(),char(),char(),char(),char()},'undefined' | char()} | {'topology_change','new_node' | 'removed_node' | 'undefined','undefined' | {byte(),byte(),byte(),byte()} | {char(),char(),char(),char(),char(),char(),char(),char()},'undefined' | char()} is expected