[bird graceful restart time] Is there any way to set graceful restart time?

Hello, We use BIRD for communication with servers with higher-level switches. In our config , there is config to set graceful restart like below. protocol bgp example2 {         import all;         export all;         ...         graceful restart on; } As far as I know, the default value for graceful restart is 120 seconds. But I don't know how to change this time. Please give me some advice on this. Thank you.