Increase strictness of NULL parameter validity in GCM's doxygen
@@ -141,9 +141,8 @@ int mbedtls_gcm_setkey( mbedtls_gcm_context *ctx,
* \param iv The initialization vector. This must be a readable buffer of
* at least \p iv_len Bytes.
* \param iv_len The length of the IV.
- * \param add The buffer holding the additional data. If \p add_len is
- * greater than zero, this must be of at least that size in
- * Bytes. If `add_len == 0`, this may be \c NULL.
+ * \param add The buffer holding the additional data. This must be of at
+ * least that size in Bytes.
* \param add_len The length of the additional data.
* \param input The buffer holding the input data. If \p length is greater
* than zero, this must be a readable buffer of at least that
@@ -188,9 +187,8 @@ int mbedtls_gcm_crypt_and_tag( mbedtls_gcm_context *ctx,
* \param iv The initialization vector. This must be a readable buffer
* of at least \p iv_len Bytes.
* \param iv_len The length of the IV.
- * \param add The buffer holding the additional data. If \p add_len is
- * greater than zero, this must be of at least that size in
- * Bytes. If `add_len == 0`, this may be \c NULL.
+ * \param add The buffer holding the additional data. This must be of at
+ * least that size in Bytes.
* \param add_len The length of the additional data.
* \param tag The buffer holding the tag to verify. This must be a
* readable buffer of at least \p tag_len Bytes.
