public final void updateAppKey(final int position, final String applicationKey) {
        if (this.appKeys.contains(applicationKey))
            throw new IllegalArgumentException("App key already exists");

        this.appKeys.set(position, applicationKey);
        saveApplicationKeys();
    }
Updates an application key

@param position       Position would be used as the key for the application key. Also during configuration steps position value would be used as the index for the application key index.
@param applicationKey application key to be added in the specified position
mesh/src/main/java/no/nordicsemi/android/mesh/ProvisioningSettings.java