This event is triggered when a GATT Client application is registered using `esp_ble_gattc_app_register`.
This event is triggered when a GATT Client application is unregistered using `esp_ble_gattc_app_unregister`.
This event is triggered when a GATT virtual connection is set up using `esp_ble_gattc_open`.
This event is triggered upon the completion of a GATT characteristic read operation using `esp_ble_gattc_read_char`.
This event is triggered upon the completion of a GATT characteristic write operation using `esp_ble_gattc_write_char`.
This event is triggered when a GATT virtual connection is closed via `esp_ble_gattc_close`, or when the physical connection is terminated.
This event is triggered upon the completion of a service discovery using `esp_ble_gattc_search_service`.
This event is triggered each time a service result is obtained using `esp_ble_gattc_search_service`.
This event is triggered upon the completion of a GATT characteristic descriptor read operation using `esp_ble_gattc_read_char_descr`.
This event is triggered upon the completion of a GATT characteristic descriptor write operation using `esp_ble_gattc_write_char_descr`.
This event is triggered when a GATT notification or indication is received from the Server.
This event is triggered upon the completion of a GATT prepare-write operation using `esp_ble_gattc_prepare_write`.
This event is triggered upon the completion of a GATT write execution using `esp_ble_gattc_execute_write` .
This event is triggered when a service changed indication is received from the Server, indicating that the attribute database on the Server has been modified (e.g., services have been added, removed).
This event is triggered upon the completion of the MTU configuration with `esp_ble_gattc_send_mtu_req`.
This event is triggered when the GATT connection is congested.
This event is triggered upon the completion of a service notification registration using `esp_ble_gattc_register_for_notify`.
This event is triggered upon the completion of a service notification unregistration using `esp_ble_gattc_unregister_for_notify`.
This event is triggered when the physical connection is set up.
This event is triggered when the physical connection is terminated.
This event is triggered when the multiple characteristic or descriptor values are retrieved using `esp_ble_gattc_read_multiple`.
This event is triggered when the GATTC command queue is full.
This event is triggered when the association between the source and the remote address is added or deleted using `esp_ble_gattc_cache_assoc`.
This event is triggered when retrieving the address list from the GATTC cache is completed using `esp_ble_gattc_cache_get_addr_list`.
This event is triggered when the GATT service discovery is completed.
This event is triggered when multiple variable length characteristic values are retrieved using `esp_ble_gattc_read_multiple`.