public boolean isEmpty() {
        boolean isEmpty = true;
        for (SortedSet<?> plugins : allPlugins) {
            isEmpty = isEmpty && plugins.isEmpty();
        }
        return isEmpty;
    }
Merge one or more {@link PluginScanResult results} into one result object
connect/runtime/src/main/java/org/apache/kafka/connect/runtime/isolation/PluginScanResult.java