KEYCHAIN/6/KEYCH_KEY_DEFAULT_A:In keychain [keychain-name], the status of default send key-id [key-id] is changed to send active.
1. When a non-default send key-id becomes inactive and default send key-id becomes active.
2. If a key string is configured for a default send key-id when no other send key-id is active.
3. If a key-id which has valid key string is configured as default when no other send key-id is active.