private Encryptor getEncryptor() {
        return getEncryptor(false);
    }
Saves a property, optionally encrypting it

@param key
           The name of the property
@param value
           The value of the property
@param isEncrypted
           {@code true} to encrypt the property, {@code true} to leave in plain text
@return The previous value associated with {@code key}, or {@code null} if there was no mapping for
        {@code key}.
xmppserver/src/main/java/org/jivesoftware/util/JiveProperties.java