static <T> void unpackSlot(List<T> out, Object[] elements, int slot) {
        Object value = elements[slot];
        if (value != null) {
            if (value instanceof Object[]) {
                Object[] array = (Object[]) value;
                for (Object object : array) {
                    out.add((T) object);
                }
            } else {
                out.add((T) value);
            }
        }
    }
Copy any elements in the given slot into the output list.
server-common/src/main/java/org/apache/kafka/timeline/BaseHashTable.java