update parameter name to camelize lower

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/CSharpClientCodegen.java

@@ -163,8 +163,24 @@ public class CSharpClientCodegen extends DefaultCodegen implements CodegenConfig
 
     @Override
     public String toParamName(String name) {
-        // should be the same as variable name
-        return toVarName(name);
+        // replace - with _ e.g. created-at => created_at
+        name = name.replaceAll("-", "_");
+
+        // if it's all uppper case, do nothing
+        if (name.matches("^[A-Z_]*$")) {
+            return name;
+        }
+
+        // camelize(lower) the variable name
+        // pet_id => petId
+        name = camelize(name, true);
+
+        // for reserved word or word starting with number, append _
+        if (reservedWords.contains(name) || name.matches("^\\d.*")) {
+            name = escapeReservedWord(name);
+        }
+
+        return name;
     }
 
     @Override