Merge "Return null on getPrivateKey failure not exception"

    /**

     * Returns the {@code PrivateKey} for the requested alias, or null

     * if no there is no result.

     * if there is no result.

     *

     * <p> This method may block while waiting for a connection to another process, and must never

     * be called from the main thread.

            final IKeyChainService keyChainService = keyChainConnection.getService();

            final String keyId = keyChainService.requestPrivateKey(alias);

            if (keyId == null) {

                throw new KeyChainException("keystore had a problem");

                return null;

            }

            return AndroidKeyStoreProvider.loadAndroidKeyStorePrivateKeyFromKeystore(

                    KeyStore.getInstance(), keyId, KeyStore.UID_SELF);