feat: java codegen for optional command arg

Author: kuhe

smithy-typescript-codegen-test/model/weather/main.smithy

@@ -167,17 +167,17 @@ apply GetCity @httpResponseTests([
         code: 200
         body: """
             {
-                "name": "Seattle",
-                "coordinates": {
-                    "latitude": 12.34,
-                    "longitude": -56.78
-                },
-                "city": {
-                    "cityId": "123",
-                    "name": "Seattle",
-                    "number": "One",
-                    "case": "Upper"
-                }
+            "name": "Seattle",
+            "coordinates": {
+            "latitude": 12.34,
+            "longitude": -56.78
+            },
+            "city": {
+            "cityId": "123",
+            "name": "Seattle",
+            "number": "One",
+            "case": "Upper"
+            }
             }"""
         bodyMediaType: "application/json"
         params: {
@@ -259,8 +259,8 @@ apply NoSuchResource @httpResponseTests([
         code: 404
         body: """
             {
-                "resourceType": "City",
-                "message": "Your custom message"
+            "resourceType": "City",
+            "message": "Your custom message"
             }"""
         bodyMediaType: "application/json"
         params: { resourceType: "City", message: "Your custom message" }

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/ServiceAggregatedClientGenerator.java

@@ -94,19 +94,27 @@ public void run() {
                 writer.writeDocs(
                     "@see {@link " + operationSymbol.getName() + "}"
                 );
-                writer.write("$L(\n"
-                            + "  args: $T,\n"
-                            + "  options?: $T,\n"
-                            + "): Promise<$T>;", methodName, input, applicationProtocol.getOptionsType(), output);
-                writer.write("$L(\n"
-                             + "  args: $T,\n"
-                             + "  cb: (err: any, data?: $T) => void\n"
-                             + "): void;", methodName, input, output);
-                writer.write("$L(\n"
-                            + "  args: $T,\n"
-                            + "  options: $T,\n"
-                            + "  cb: (err: any, data?: $T) => void\n"
-                            + "): void;", methodName, input, applicationProtocol.getOptionsType(), output);
+                writer.addImport("OptionalParameter", null, TypeScriptDependency.SMITHY_TYPES);
+                writer.write("""
+                    $L(
+                      ...[args]: OptionalParameter<$T>,
+                    ): Promise<$T>;""", methodName, input, output);
+                writer.write("""
+                    $L(
+                      args: $T,
+                      options?: $T,
+                    ): Promise<$T>;""", methodName, input, applicationProtocol.getOptionsType(), output);
+                writer.write("""
+                    $L(
+                      args: $T,
+                      cb: (err: any, data?: $T) => void
+                    ): void;""", methodName, input, output);
+                writer.write("""
+                    $L(
+                      args: $T,
+                      options: $T,
+                      cb: (err: any, data?: $T) => void
+                    ): void;""", methodName, input, applicationProtocol.getOptionsType(), output);
                 writer.write("");
             }
         });