Fix enum variant name generation

Datatypes like `Vec<foo::bar::Baz>` would end up as `Baz` instead of `VecOfBaz`

Author: whirm

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RustAxumServerCodegen.java

@@ -615,8 +615,9 @@ private void postProcessOneOfModels(List<ModelMap> allModels) {
  for (CodegenProperty model : csOneOf) {
  // Generate a valid name for the enum variant.
  // Mainly needed for primitive types.
- String[] modelParts = model.dataType.replace("<", "Of").replace(">", "").split("::");
- model.datatypeWithEnum = camelize(modelParts[modelParts.length - 1]);
+
+ model.datatypeWithEnum = camelize(model.dataType.replaceAll("(?:\\w+::)+(\\w+)", "$1")
+ .replace("<", "Of").replace(">", ""));
 
  // Primitive type is not properly set, this overrides it to guarantee adequate model generation.
  if (!model.getDataType().matches(String.format(Locale.ROOT, ".*::%s", model.getDatatypeWithEnum()))) {