HI-118 workaround - deep merges are not supported properly in automatic parameter lookup

profile_mysql_server.pp

# When using an externally provided module like mysql::server, we cannot modify the parameter lookups in the module.
# As a compromise, do lookups in our wrapper profile class and then pass on the values
class profile::mysql::server (
  $override_options = hiera_hash('mysql_server_override_options', {}),
  $users            = hiera_hash('mysql_server_users', {}),
  $grants           = hiera_hash('mysql_server_grants', {}),
  $databases        = hiera_hash('mysql_server_databases', {}),
) {
  # ...do stuff...
  
  # We have to instantiate the class rather than include it to pass values.
  class {'::mysql::server':
    override_options => $override_options,
    users => $users,
    grants => $grants,
    databases => $databases,
  }
  include ::mysql::server::backup
  include ::mysql::server::account_security
}

your_own_class.pp

# When we make our own class that we want others to consume, or if we were able to contribute to an externally provided module,
# we can look up our own class's options with hiera_hash *in* the class parameters.
class your::own::class (
  $option = hiera_hash('your::own::class::option', undef),
) {
  # ...do stuff..
}

# In another class, "include ::your::own::class" works just fine even with deep merge.