public default String getIdentifier() {
        UUID uuid = getUUID();
        return uuid != null ? uuid.toString() : null;
    }
Returns the unique identifier assigned to this record, if any. If this
record is not uniquely identifiable, this may be null. If provided, this
unique identifier MUST be unique across all {@link ActivityRecord}
objects within the same {@link ActivityRecordSet}.

@return
    The unique identifier assigned to this record, or null if this
    record has no such identifier.
guacamole-ext/src/main/java/org/apache/guacamole/net/auth/ActivityRecord.java