ForEach: add default value {"item1", "item2"} for Elements parameter

Prevents immediate validation error when node is added before user has a chance to fill in the field.

Author: Kuba Nowakowski

engine/flink/components/base/src/main/scala/pl/touk/nussknacker/engine/flink/util/transformer/ForEachTransformer.scala

@@ -20,7 +20,7 @@ object ForEachTransformer extends CustomStreamTransformer with Serializable {
 
   @MethodToInvoke(returnType = classOf[Object])
   def invoke(
-      @ParamName("Elements") elements: LazyParameter[util.Collection[AnyRef]],
+      @ParamName("Elements") @DefaultValue("{\"item1\", \"item2\"}") elements: LazyParameter[util.Collection[AnyRef]],
       @OutputVariableName outputVariable: String
   ): FlinkCustomStreamTransformation with ReturningType = {
     FlinkCustomStreamTransformation(

engine/lite/components/base/src/main/scala/pl/touk/nussknacker/engine/lite/components/ForEachTransformer.scala

@@ -15,7 +15,7 @@ object ForEachTransformer extends CustomStreamTransformer {
 
   @MethodToInvoke(returnType = classOf[Object])
   def invoke(
-      @ParamName("Elements") elements: LazyParameter[java.util.Collection[Any]],
+      @ParamName("Elements") @DefaultValue("{\"item1\", \"item2\"}") elements: LazyParameter[java.util.Collection[Any]],
       @OutputVariableName outputVariable: String
   ): LiteCustomComponent = {
     new ForEachTransformerComponent(elements, outputVariable)