advanced_https_ota_example: Demonstrate use of init_complete_callback to set custom headers

examples/system/ota/advanced_https_ota/main/advanced_https_ota_example.c

@@ -52,6 +52,14 @@ static esp_err_t validate_image_header(esp_app_desc_t *new_app_info)
     return ESP_OK;
 }
 
+static esp_err_t _http_client_init_cb(esp_http_client_handle_t http_client)
+{
+    esp_err_t err = ESP_OK;
+    /* Uncomment to add custom headers to HTTP request */
+    // err = esp_http_client_set_header(http_client, "Custom-Header", "Value");
+    return err;
+}
+
 void advanced_ota_example_task(void *pvParameter)
 {
     ESP_LOGI(TAG, "Starting Advanced OTA example");
@@ -83,6 +91,7 @@ void advanced_ota_example_task(void *pvParameter)
 
     esp_https_ota_config_t ota_config = {
         .http_config = &config,
+        .http_client_init_cb = _http_client_init_cb, // Register a callback to be invoked after esp_http_client is initialized
     };
 
     esp_https_ota_handle_t https_ota_handle = NULL;