Make StoredSecret AutoCloseable

[ackasaber]

StoredSecret interface looks like a good candidate to be AutoCloseable. So instead of this abomination from the sample code

private void userLogin() {
    log.info("Authenticating a user");

    final StoredCredential enteredCredential = enterCredentials();
    StoredCredential storedCredential = null;

    try {
        // Save the credential to the store.
        storedCredential = credentialStorage.get(CREDENTIALS_KEY);

        if (storedCredential.equals(enteredCredential)) {
            log.info("User logged in successfully.");
        } else {
            log.info("Authentication failed.");
        }
    } finally {
        // clear password value
        enteredCredential.clear();

        if (storedCredential != null) {
            storedCredential.clear();
        }
    }
}

you could write this beauty

private void userLogin() {
    log.info("Authenticating a user");

    try (StoredCredential enteredCredential = enterCredentials();
         StoredCredential storedCredential = credentialStorage.get(CREDENTIALS_KEY)) {

        if (storedCredential.equals(enteredCredential)) {
            log.info("User logged in successfully.");
        } else {
            log.info("Authentication failed.");
        }
    }
}