Marshmallow permission implementation
There is no longer need AUTHENTICATE_ACCOUNTS on Android 6.0.
you can use android:maxSdkVersion="22" on your uses-permission element to stop requesting it as of Android 6.0.
As mentioned in comment by CommonsWare Sir and this blog helped to understand more on this issue.
AUTHENTICATE_ACCOUNTS this permission no exist any more, as google project manager said.
We'll have to wait for a future preview revision to pursue this because the M revision 2 'key changes' section states: "Some accounts and identity permissions are moved to CONTACTS permissions group and others are removed or granted based on account type. In particular, android.permission.USE_CREDENTIALS, android.permission.MANAGE_ACCOUNTS, and android.permission.AUTHENTICATE_ACCOUNTS are ungrouped pending further changes in a later release." http://developer.android.com/preview/support.html