Fix greedy label param names in OpenAPI

Services like API Gateway that use "greedy" labels require that bath
the segment and the corresponding parameter name contain a "+". We
previously included the "+" in the URI label but not in the parameter
name.

smithy-openapi/src/main/java/software/amazon/smithy/openapi/fromsmithy/protocols/AbstractRestProtocol.java

@@ -29,6 +29,7 @@
 import software.amazon.smithy.model.knowledge.HttpBinding;
 import software.amazon.smithy.model.knowledge.HttpBindingIndex;
 import software.amazon.smithy.model.knowledge.OperationIndex;
+import software.amazon.smithy.model.pattern.SmithyPattern;
 import software.amazon.smithy.model.shapes.CollectionShape;
 import software.amazon.smithy.model.shapes.MemberShape;
 import software.amazon.smithy.model.shapes.OperationShape;
@@ -38,6 +39,7 @@
 import software.amazon.smithy.model.traits.HttpTrait;
 import software.amazon.smithy.model.traits.TimestampFormatTrait;
 import software.amazon.smithy.model.traits.Trait;
+import software.amazon.smithy.openapi.OpenApiException;
 import software.amazon.smithy.openapi.fromsmithy.Context;
 import software.amazon.smithy.openapi.fromsmithy.OpenApiProtocol;
 import software.amazon.smithy.openapi.model.MediaTypeObject;
@@ -120,10 +122,26 @@ public Optional<Operation> createOperation(Context<T> context, OperationShape op
     private List<ParameterObject> createPathParameters(Context<T> context, OperationShape operation) {
         List<ParameterObject> result = new ArrayList<>();
         HttpBindingIndex bindingIndex = HttpBindingIndex.of(context.getModel());
+        HttpTrait httpTrait = operation.expectTrait(HttpTrait.class);
 
         for (HttpBinding binding : bindingIndex.getRequestBindings(operation, HttpBinding.Location.LABEL)) {
             Schema schema = createPathParameterSchema(context, binding);
+            String memberName = binding.getMemberName();
+
+            SmithyPattern.Segment label = httpTrait.getUri()
+                    .getLabel(memberName)
+                    .orElseThrow(() -> new OpenApiException(String.format(
+                            "Unable to find URI label on %s for %s: %s",
+                            operation.getId(),
+                            binding.getMemberName(),
+                            httpTrait.getUri())));
+
+            // Greedy labels in OpenAPI need to include the label in the generated parameter.
+            // For example, given "/{foo+}", the parameter name must be "foo+".
+            String name = label.isGreedyLabel() ? label.getContent() + "+" : label.getContent();
+
             result.add(ModelUtils.createParameterMember(context, binding.getMember())
+                    .name(name)
                     .in("path")
                     .schema(schema)
                     .build());

smithy-openapi/src/test/java/software/amazon/smithy/openapi/fromsmithy/protocols/AwsRestJson1ProtocolTest.java

@@ -27,7 +27,8 @@ public class AwsRestJson1ProtocolTest {
             "adds-header-mediatype-format.json",
             "supports-payloads.json",
             "aws-rest-json-uses-jsonname.json",
-            "synthesizes-contents.json"
+            "synthesizes-contents.json",
+            "greedy-labels.json"
     })
 
     public void testProtocolResult(String smithy) {

smithy-openapi/src/test/resources/software/amazon/smithy/openapi/fromsmithy/protocols/greedy-labels.json

@@ -0,0 +1,48 @@
+{
+    "smithy": "1.0",
+    "shapes": {
+        "smithy.example#Service": {
+            "type": "service",
+            "version": "2006-03-01",
+            "operations": [
+                {
+                    "target": "smithy.example#Operation"
+                }
+            ],
+            "traits": {
+                "aws.protocols#restJson1": {}
+            }
+        },
+        "smithy.example#Operation": {
+            "type": "operation",
+            "input": {
+                "target": "smithy.example#OperationInput"
+            },
+            "traits": {
+                "smithy.api#http": {
+                    "uri": "/{foo}/{baz+}",
+                    "method": "POST"
+                }
+            }
+        },
+        "smithy.example#OperationInput": {
+            "type": "structure",
+            "members": {
+                "foo": {
+                    "target": "smithy.api#String",
+                    "traits": {
+                        "smithy.api#required": {},
+                        "smithy.api#httpLabel": {}
+                    }
+                },
+                "baz": {
+                    "target": "smithy.api#String",
+                    "traits": {
+                        "smithy.api#required": {},
+                        "smithy.api#httpLabel": {}
+                    }
+                }
+            }
+        }
+    }
+}

smithy-openapi/src/test/resources/software/amazon/smithy/openapi/fromsmithy/protocols/greedy-labels.openapi.json

@@ -0,0 +1,37 @@
+{
+    "openapi": "3.0.2",
+    "info": {
+        "title": "Service",
+        "version": "2006-03-01"
+    },
+    "paths": {
+        "/{foo}/{baz+}": {
+            "post": {
+                "operationId": "Operation",
+                "parameters": [
+                    {
+                        "name": "foo",
+                        "in": "path",
+                        "schema": {
+                            "type": "string"
+                        },
+                        "required": true
+                    },
+                    {
+                        "name": "baz+",
+                        "in": "path",
+                        "schema": {
+                            "type": "string"
+                        },
+                        "required": true
+                    }
+                ],
+                "responses": {
+                    "200": {
+                        "description": "Operation response"
+                    }
+                }
+            }
+        }
+    }
+}