private static void detectMetadataChanges(Model oldModel, Model newModel, Differences differences) {
        oldModel.getMetadata().forEach((k, v) -> {
            if (newModel.getMetadata().containsKey(k) && !newModel.getMetadata().get(k).equals(v)) {
                differences.changedMetadata.add(new ChangedMetadata(k, v, newModel.getMetadata().get(k)));
            }
        });
    }
Gets a stream of all changed metadata.

@return Returns the changed metadata.
smithy-diff/src/main/java/software/amazon/smithy/diff/Differences.java