Change how KeyNotInstalledException check works

I am implementing my own TextEncryptor and in order for it to work I must verify that the caller passed in a key. What I noticed was that in the EncryptionController there is a method checkEncryptorInstalled(...) which tries to locate a TextEncryptor and then does a dummy encryption to make sure that the NoOpTextEncryptor is not being used. This breaks me because the checkEncryptorInstalled(...) method does not pass in the parsed "encryptorKeys". Also, the dummy encryption call concerns me because I am using AWS Key Management Service so I would not want to do a dummy encryption every time the encrypt endpoint is called.

Would it make more sense to instead check to see if a TextEncryptorLocator bean exists, and if not, then throw the KeyNotInstalledException such as below? This would mean removing the NoOpTextEncryptor, and SingleTextEncryptorLocator from being autoconfigured unless if the "encrypt.key" system property was set.

OLD:

private void checkEncryptorInstalled(String name, String profiles) {
    if (this.encryptor == null || this.encryptor.locate(this.helper.getEncryptorKeys(name, profiles, ""))
        .encrypt("FOO").equals("FOO")) {
            throw new KeyNotInstalledException();
    }
}

NEW:

private void checkEncryptorInstalled(String name, String profiles) {
    if (this.encryptor == null) {
            throw new KeyNotInstalledException();
    }
}

Start at EncryptionController.checkEncryptorInstalled(...) and trace how NoOpTextEncryptor and SingleTextEncryptorLocator are autoconfigured. Determine how the parsed "encryptorKeys" reach the custom TextEncryptor, then verify that missing-key handling avoids dummy encryption and still raises KeyNotInstalledException when appropriate.