Document saving 5~6 times during issuance

[cindy-chin]

Hi, from my side I find it is strange that using the multipaz/android identity lib that will trigger overwriting the document 5-6 times while saving, Imagine in future SE will be involve in encryption and decryption, it will have huge impact on the performance, since every saving need encrypt the whole document again, and it will happens 5-6 times.