fix(go): only import reflect when using it (OpenAPITools#19967)

The api.mustache template only uses the reflect package if there is a
query parameter which `isCollectionFormatMulti`. The import for the
reflect package is however added if _any_ parameter is
`isCollectionFormatMulti`.

If the parameter which `isCollectionFormatMulti` e.g. is in the body
instead of the query, this leads to the import being part of the
generated code but not used and the code does not compile.

This updates reworks the import handling for the `reflect` package so
that it is only added if there is a query parameter which
`isCollectionFormatMulti`.

Co-authored-by: Per Hallgren <[email protected]>

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractGoCodegen.java

@@ -558,12 +558,6 @@ public OperationsMap postProcessOperationsWithModels(OperationsMap objs, List<Mo
                     addedTimeImport = true;
                 }
 
-                // import "reflect" package if the parameter is collectionFormat=multi
-                if (!addedReflectImport && param.isCollectionFormatMulti) {
-                    imports.add(createMapping("import", "reflect"));
-                    addedReflectImport = true;
-                }
-
                 // set x-exportParamName
                 char nameFirstChar = param.paramName.charAt(0);
                 if (Character.isUpperCase(nameFirstChar)) {
@@ -577,6 +571,14 @@ public OperationsMap postProcessOperationsWithModels(OperationsMap objs, List<Mo
                 }
             }
 
+            for (CodegenParameter param : operation.queryParams) {
+                // import "reflect" package if the parameter is collectionFormat=multi
+                if (!addedReflectImport && param.isCollectionFormatMulti) {
+                    imports.add(createMapping("import", "reflect"));
+                    addedReflectImport = true;
+                }
+            }
+
             setExportParameterName(operation.queryParams);
             setExportParameterName(operation.formParams);
             setExportParameterName(operation.headerParams);