title: Can we link the GranteePrincipal from List Grants API back to User/Role which is issued the grant?
body: <p>In the Amazon Key Management Service there is away to list grants on a Customer Master Key. This returns a list of GrantListEntry objects. Each one has a getGranteePrincipal() method which returns a string simmilar to <code>AIDAJBVZPN4EIJ44R7AZM</code>. This is supposed to map to the user/role for which this grant is relevant however, I cannot figure out how to map this string to a user. It is not their IAM key or ARN. Is there any way to correlate this string to the original user?</p>