use camelize method for model names

Author: HugoMario

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

@@ -466,7 +466,7 @@ public String toModelName(final String name) {
         String modifiedName = name.replaceAll("\\.", "");
         modifiedName = sanitizeKotlinSpecificNames(modifiedName);
 
-        modifiedName = titleCase(modifiedName);
+        modifiedName = camelize(modifiedName);
 
         if (modifiedName.equalsIgnoreCase("Companion")) {
             modifiedName = "_" + modifiedName;