refine TemplateFilter type

Signed-off-by: Matt Benson <gudnabrsam@gmail.com>

plugins/scaffolder-backend/src/lib/templating/SecureTemplater.ts

@@ -190,7 +190,8 @@ export class SecureTemplater {
         if (!Object.hasOwn(templateFilters, filterName)) {
           return '';
         }
-        const rz = templateFilters[filterName](...args);
+        const [input, ...rest] = args;
+        const rz = templateFilters[filterName](input, ...rest);
         return rz === undefined ? '' : JSON.stringify(rz);
       },
     );

plugins/scaffolder-node/src/types.ts

@@ -17,7 +17,10 @@
 import { JsonValue } from '@backstage/types';
 
 /** @public */
-export type TemplateFilter = (...args: JsonValue[]) => JsonValue | undefined;
+export type TemplateFilter = (
+  arg: JsonValue,
+  ...rest: JsonValue[]
+) => JsonValue | undefined;
 
 /** @public */
 export type TemplateGlobal =