+ * <td>stt_set_credential()</td>
+ * <td>Created, Ready</td>
+ * <td></td>
+ * </tr>
+ * <tr>
+ * <td>stt_set_private_data()<br>stt_get_private_data()</td>
+ * <td>Ready</td>
+ * <td></td>
+ * </tr>
+ * <tr>
+ * <td>stt_get_error_message()</td>
+ * <td>Created, Ready, Recording, Processing</td>
+ * <td>This function should be called during STT error callback.</td>
+ * </tr>
+ * <tr>