Methods GetUsersFromEmail and GetUserFromLoginName are missing in Litium 6

What is the replacement for the methods: Solution.Instance.Users.GetUsersFromEmail and Solution.Instance.Users.GetUserFromLoginName that were avaliable in Litium 4.8?

Litium version: 6

Litium.Security.SecurityContextService has a method to fetch PersonSystemId by username.

E-mail is stored on person in a field with key Litium.FieldFramework.SystemFieldDefinitionConstants.Email.