@Override
    public boolean equals(Object o) {
        if (o == this) return true;
        if (!(o instanceof UserIdentifier)) return false;
        final UserIdentifier other = (UserIdentifier) o;
        return this.uniqueId.equals(other.uniqueId);
    }
Creates a {@link UserIdentifier}.

@param uniqueId the uuid of the user
@param username the username of the user, nullable
@return a new identifier
common/src/main/java/me/lucko/luckperms/common/model/UserIdentifier.java