fix(endpoint): deduplicate client context and built-in params with the same name (smithy-lang#616)

Author: kuhe

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

@@ -20,6 +20,7 @@
 import static software.amazon.smithy.typescript.codegen.CodegenUtils.writeClientCommandStreamingOutputType;
 
 import java.nio.file.Paths;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -191,18 +192,8 @@ private void generateEndpointParameterInstructionProvider() {
                     "return {", "};",
                     () -> {
                         RuleSetParameterFinder parameterFinder = new RuleSetParameterFinder(service);
-                        parameterFinder.getBuiltInParams().forEach((name, type) -> {
-                            writer.write(
-                                "$L: { type: \"builtInParams\", name: \"$L\" },",
-                                name, EndpointsParamNameMap.getLocalName(name)
-                            );
-                        });
-                        parameterFinder.getClientContextParams().forEach((name, type) -> {
-                            writer.write(
-                                "$L: { type: \"clientContextParams\", name: \"$L\" },",
-                                name, EndpointsParamNameMap.getLocalName(name)
-                            );
-                        });
+                        Set<String> paramNames = new HashSet<>();
+
                         Shape operationInput = model.getShape(operation.getInputShape()).get();
                         parameterFinder.getStaticContextParamValues(operationInput).forEach((name, value) -> {
                             writer.write(
@@ -216,6 +207,24 @@ private void generateEndpointParameterInstructionProvider() {
                                 name, EndpointsParamNameMap.getLocalName(name)
                             );
                         });
+                        parameterFinder.getClientContextParams().forEach((name, type) -> {
+                            if (!paramNames.contains(name)) {
+                                writer.write(
+                                    "$L: { type: \"clientContextParams\", name: \"$L\" },",
+                                    name, EndpointsParamNameMap.getLocalName(name)
+                                );
+                            }
+                            paramNames.add(name);
+                        });
+                        parameterFinder.getBuiltInParams().forEach((name, type) -> {
+                            if (!paramNames.contains(name)) {
+                                writer.write(
+                                    "$L: { type: \"builtInParams\", name: \"$L\" },",
+                                    name, EndpointsParamNameMap.getLocalName(name)
+                                );
+                            }
+                            paramNames.add(name);
+                        });
                     }
                 );
             }

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/endpointsV2/EndpointsParamNameMap.java

@@ -38,6 +38,21 @@ public static void addNameMapping(Map<String, String> parameterNameMap) {
     }
 
     public static String getLocalName(String endpointsV2ParamName) {
-        return MAPPING.getOrDefault(endpointsV2ParamName, endpointsV2ParamName);
+        boolean isTitleCase = false;
+        if (endpointsV2ParamName.length() >= 2) {
+            String char1 = endpointsV2ParamName.substring(0, 1);
+            String char2 = endpointsV2ParamName.substring(1, 2);
+            if (char1.toUpperCase().equals(char1) && char2.toLowerCase().equals(char2)) {
+                isTitleCase = true;
+            }
+        }
+
+        String suggestedName = endpointsV2ParamName;
+        if (isTitleCase) {
+            suggestedName = endpointsV2ParamName.substring(0, 1).toLowerCase()
+                + endpointsV2ParamName.substring(1);
+        }
+
+        return MAPPING.getOrDefault(endpointsV2ParamName, suggestedName);
     }
 }