Is your feature request related to a problem? Please describe.

We use https://github.com/daichirata/hammer for spanner schema management, which in turn uses spanner/spansql. If we set the default_leader as described in https://cloud.google.com/spanner/docs/modifying-leader-region hammer will fail to parse the ddl and we can no longer manage our schemas with it.

Describe the solution you'd like

Add support for default_leader database option.