@Override
    public String toString() {
        // Values are intentionally left out of this so that sensitive configs
        // do not end up in logging by mistake.
        return "ConfigurationDelta(" +
            "changedKeys=" + changes.keySet() +
            ')';
    }
Represents changes to the configurations in the metadata image.
metadata/src/main/java/org/apache/kafka/image/ConfigurationDelta.java