Converts an APIAuditEntry to a legacy AuditEvent.

def _EntryToEvent(entry, handlers, transformers):
  """Converts an APIAuditEntry to a legacy AuditEvent."""
  event = rdf_events.AuditEvent(
      timestamp=entry.timestamp,
      user=entry.username,
      action=handlers[entry.router_method_name])

  for fn in transformers:
    fn(entry, event)

  return event