clean up validation, still not happy

shared/src/validators/string-list.validator.ts

@@ -1,12 +1,9 @@
 import {
-  IsArray,
-  IsNotEmpty,
-  IsString
+  IsArray, IsString
 } from 'class-validator';
 import { CombinePDecorators } from '../util/decorator';
 
 export const IsStringList = CombinePDecorators(
   IsArray(),
   IsString({ each: true }),
-  IsNotEmpty({ each: true }),
 );