Spring Using UriComponentsBuilder.cloneBuilder does not copy uriVariables

According to the docs, when you do UriComponentsBuilder.cloneBuilder (v5.2.5.RELEASE) it should create a deep clone: https://github.com/spring-projects/spring-framework/blob/c08e31b7d613bf91cbe2beac2dad66714403faee/spring-web/src/main/java/org/springframework/web/util/UriComponentsBuilder.java#L146-L162

However, if your builder has pathSegments the uriVariables will not be preserved. Imagine the following scenario - you have a base builder which you are going to receive and you need to append path(s) to it. Here is an oversimplified example:

public UriComponentsBuilder getStorageBuilder(int userId, String storageName) {
    HashMap<String, Object> uriVariables = new HashMap<>();
    uriVariables.put("userId", userId);
    uriVariables.put("storageId", storageName);

    UriComponentsBuilder baseBuilder = ServletUriComponentsBuilder.fromCurrentRequest();
    baseBuilder.replacePath("/storages");
    baseBuilder.pathSegment("{userId}");
    baseBuilder.pathSegment("{storageName}");
    baseBuilder.uriVariables(uriVariables);

    return baseBuilder;
}
....

// Receive a configured `builder` (something else calls `getStorageBuilder` before this method and it's passed as an argument here)
public UriComponentsBuilder getStorageDirectoryListing(UriComponentsBuilder baseBuilder, String path) {
    // http://localhost/storages/%7BuserId%7D/%7BstorageName%7D/some/path
    return baseBuilder.cloneBuilder().path(path).toUriString();
}

In this case the cloned builder will not have the uriVariables copied. Furthermore, there is no getter method for the uriVariables so you can't manually copy them. A quick'n'dirty workaround to this is would be:

String fileUrl = UriComponentsBuilder.fromUriString(baseBuilder.toUriString())
                                     .path("/some/path").build().toUriString();

Unfortunately this removes the ability to change anything in the pathSegments. Is there anything I'm missing here for uriVariables to be excluded when cloning or is this simply missing at the moment?

Comment From: rstoyanchev

It looks like it's simply missing.

Comment From: jhoeller

It seems that #21565 introduced that uriVariables field in 5.0.8 but didn't include it in the cloning step. Let's backport this fix to 5.1.x and 5.0.x as well in order to close that gap in all affected branches.