fix NoMethodError in mappings after_created when synapse's topic1/topic2 are nil
fix NoMethodError in mappings after_created when synapse's topic1/topic2 are nil

metamaps/metamaps,metamaps/metamaps_gen002,metamaps/metamaps,metamaps/metamaps,metamaps/metamaps,metamaps/metamaps_gen002,metamaps/metamaps_gen002,metamaps/metamaps_gen002