Add test for MultiSelect List flatten in OperationContextParams

Author: trivikr

smithy-typescript-codegen/src/test/java/software/amazon/smithy/typescript/codegen/CommandGeneratorTest.java

@@ -45,6 +45,7 @@ public void writesOperationContextParamValues() {
                 "opContextParamWildcardExpressionListObj: { type: \"operationContextParams\", get: (input?: any) => input?.fooListObj?.map((obj: any) => obj?.key) }",
                 "opContextParamWildcardExpressionHash: { type: \"operationContextParams\", get: (input?: any) => Object.values(input?.fooObjObj ?? {}).map((obj: any) => obj?.bar) }",
                 "opContextParamMultiSelectList: { type: \"operationContextParams\", get: (input?: any) => input?.fooListObjObj?.map((obj: any) => [obj?.fooList[0],obj?.fooObject?.bar,obj?.fooString].filter((i) => i)) }",
+                "opContextParamMultiSelectListFlatten: { type: \"operationContextParams\", get: (input?: any) => input?.fooListObjObj?.map((obj: any) => [obj?.fooList].filter((i) => i).flat()) }",
                 "opContextParamKeys: { type: \"operationContextParams\", get: (input?: any) => Object.keys(input?.fooKeys ?? {}) }",
             }
         );

smithy-typescript-codegen/src/test/resources/software/amazon/smithy/typescript/codegen/endpointsV2/endpoints-operation-context-params.smithy

@@ -23,6 +23,9 @@ namespace smithy.example
         opContextParamMultiSelectList: {
             type: "stringArray",
         },
+        opContextParamMultiSelectListFlatten: {
+            type: "stringArray",
+        },
         opContextParamKeys: {
             type: "stringArray",
         },
@@ -41,6 +44,7 @@ service Example {
     "opContextParamWildcardExpressionListObj": { path: "fooListObj[*].key" }
     "opContextParamWildcardExpressionHash": { path: "fooObjObj.*.bar" }
     "opContextParamMultiSelectList": { path: "fooListObjObj[*].[fooList[0], fooObject.bar, fooString]" }
+    "opContextParamMultiSelectListFlatten": { path: "fooListObjObj[*].[fooList][]" }
     "opContextParamKeys": { path: "keys(fooKeys)" }
 )
 operation GetFoo {