NfcEngagementHelper

Helper used for NFC engagement.

This implements NFC engagement as defined in ISO/IEC 18013-5:2021.

Applications can instantiate a NfcEngagementHelper using NfcEngagementHelper.Builder to specify the NFC engagement type (static or negotiated) and other details, such as which device retrieval methods to offer with static handover.

If negotiated handover is used, Listener.onTwoWayEngagementDetected is called when the NFC tag reader has selected the connection handover service.

When a remote mdoc reader connects to either one of the transports advertised via static handover or one of the transports offered by the reader via negotiated handover, Listener.onDeviceConnected is called and the application can use the passed-in DataTransport to create a com.android.identity.android.mdoc.deviceretrieval.DeviceRetrievalHelper to start the transaction.