@Override
    public String toString() {
        return new ToStringBuilder(this)
            .append("attribute", attribute)
            .append("salt", StringUtils.abbreviate(salt, CONST_SALT_ABBREV_LENGTH))
            .toString();
    }
Determine principal id from attributes.

@param defaultId  the default id
@param attributes the attributes
@return the string
core/cas-server-core-authentication-api/src/main/java/org/apereo/cas/authentication/principal/ShibbolethCompatiblePersistentIdGenerator.java