NewIdentityUserMapper returns a UserIdentityMapper that does the following: 1.

MappingMethodAdd associates a new identity with a user with the identity's preferred username, creating the user if needed, and adding to any existing identities associated with the user.

MappingMethodClaim associates a new identity with a user with the identity's preferred username if no other identities are already associated with the user.

MappingMethodGenerate finds an available username for a new identity, based on its preferred username If a user with the preferred username already exists, a unique username is generated.

MappingMethodLookup does not provision a new identity or user, it only allows identities already associated with users.

DefaultGenerator attempts to use the base name first, then "base2", "base3", ...

MaxGenerateAttempts limits how many times we try to find an available username for a new identity.

StrategyAdd associates a new identity with a user with the identity's preferred username, adding to any existing identities associated with the user.

StrategyClaim associates a new identity with a user with the identity's preferred username if no other identities are already associated with the user.

StrategyGenerate finds an available username for a new identity, based on its preferred username If a user with the preferred username already exists, a unique username is generated.

Initializer is responsible for initializing fields in a User API object from its associated Identity.

UserForNewIdentityGetter is responsible for creating or locating the persisted User for the given Identity.

UserNameGenerator returns a username.