fix: support both array and string inputs in parameter validation

- Add getArraySize helper method
- Maintain array handling in query parameters
- Fix backwards compatibility from PR jlevers#700

Fixes jlevers#831

lib/Api/CatalogItemsV20220401Api.php

@@ -13,7 +13,7 @@
  * The Selling Partner API for Catalog Items provides programmatic access to information about items in the Amazon catalog. For more information, refer to the [Catalog Items API Use Case Guide](https://developer-docs.amazon.com/sp-api/docs/catalog-items-api-v2022-04-01-use-case-guide).
  *
  * The version of the OpenAPI document: 2022-04-01
- * 
+ *
  * Generated by: https://openapi-generator.tech
  * OpenAPI Generator version: 5.0.1
  */
@@ -283,7 +283,7 @@ public function getCatalogItemWithHttpInfo($asin, $marketplace_ids, $included_da
     /**
      * Operation getCatalogItemAsync
      *
-     * 
+     *
      *
      * @param  string $asin The Amazon Standard Identification Number (ASIN) of the item. (required)
      * @param  string[] $marketplace_ids A comma-delimited list of Amazon marketplace identifiers. Data sets in the response contain data only for the specified marketplaces. (required)
@@ -301,7 +301,7 @@ public function getCatalogItemAsync($asin, $marketplace_ids, $included_data = nu
     /**
      * Operation getCatalogItemAsyncWithHttpInfo
      *
-     * 
+     *
      *
      * @param  string $asin The Amazon Standard Identification Number (ASIN) of the item. (required)
      * @param  string[] $marketplace_ids A comma-delimited list of Amazon marketplace identifiers. Data sets in the response contain data only for the specified marketplaces. (required)
@@ -737,7 +737,7 @@ public function searchCatalogItemsWithHttpInfo($marketplace_ids, $identifiers =
     /**
      * Operation searchCatalogItemsAsync
      *
-     * 
+     *
      *
      * @param  string[] $marketplace_ids A comma-delimited list of Amazon marketplace identifiers for the request. (required)
      * @param  string[] $identifiers A comma-delimited list of product identifiers to search the Amazon catalog for. **Note:** Cannot be used with `keywords`. (optional)
@@ -763,7 +763,7 @@ public function searchCatalogItemsAsync($marketplace_ids, $identifiers = null, $
     /**
      * Operation searchCatalogItemsAsyncWithHttpInfo
      *
-     * 
+     *
      *
      * @param  string[] $marketplace_ids A comma-delimited list of Amazon marketplace identifiers for the request. (required)
      * @param  string[] $identifiers A comma-delimited list of product identifiers to search the Amazon catalog for. **Note:** Cannot be used with `keywords`. (optional)
@@ -853,15 +853,16 @@ public function searchCatalogItemsRequest($marketplace_ids, $identifiers = null,
                 'Missing the required parameter $marketplace_ids when calling searchCatalogItems'
             );
         }
-        if (count( explode(",", $marketplace_ids) ) > 1) {
+
+        if ($this->getMarketplaceCount($marketplace_ids) > 1) {
             throw new \InvalidArgumentException('invalid value for "$marketplace_ids" when calling CatalogItemsV20220401Api.searchCatalogItems, number of items must be less than or equal to 1.');
         }
 
-        if ($identifiers !== null && count( explode(",", $identifiers) ) > 20) {
+        if ($identifiers !== null && $this->getMarketplaceCount($identifiers) > 20) {
             throw new \InvalidArgumentException('invalid value for "$identifiers" when calling CatalogItemsV20220401Api.searchCatalogItems, number of items must be less than or equal to 20.');
         }
 
-        if ($keywords !== null && count( explode(",", $keywords) ) > 20) {
+        if ($keywords !== null && $this->getMarketplaceCount($keywords) > 20) {
             throw new \InvalidArgumentException('invalid value for "$keywords" when calling CatalogItemsV20220401Api.searchCatalogItems, number of items must be less than or equal to 20.');
         }
 
@@ -1029,4 +1030,14 @@ public function searchCatalogItemsRequest($marketplace_ids, $identifiers = null,
         );
     }
 
+    /**
+     * Get the marketplace count demanded by the value type
+     *
+     * @param $value
+     * @return int
+     */
+    private function getMarketplaceCount($value): int
+    {
+        return is_array($value) ? count($value) : count(explode(",", (string)$value));
+    }
 }