hi, I'm working in a new cryptocurrency exchange, and we are planning to support BTS.

I have created a private testnet using my own "genesis.json" in which the initial_timestamp is 2018-05-12T09:47:40,

But the command "get_dynamic_global_properties" in cli_wallet returned :
...
  "time": "2018-05-12T09:47:40",
  "current_witness": "1.6.0",
  "next_maintenance_time": "1970-01-01T00:00:00",
  "last_budget_time": "1970-01-01T00:00:00",
...

why dose the "next_maintenance_time" come to be "1970-01-01T00:00:00"(my system time is correct)?