hollow/src/main/java/com/netflix/hollow/core/memory/encoding/FixedLengthMultipleOccurrenceElementArray.java
public List<Long> getElements(long nodeIndex) {
        long bucketStart = nodeIndex * maxElementsPerNode * bitsPerElement;
        List<Long> ret = new ArrayList<>();
        if (nodesWithOrdinalZero.getElementValue(nodeIndex, 1, 1) != NO_ELEMENT) {
            // 0 indicates an "empty" element, so we fetch ordinal zeros from nodesWithOrdinalZero
            ret.add(NO_ELEMENT);
        }
        for (int offset = 0; offset < maxElementsPerNode; offset++) {
            long element = storage.getElementValue(bucketStart + offset * bitsPerElement,
                    bitsPerElement, elementMask);
            if (element == NO_ELEMENT) {
                break; // we have exhausted the elements at this index
            }
            ret.add(element);
        }
        return ret;
    }
public List<Long> getElements(long nodeIndex) {
        long bucketStart = nodeIndex * maxElementsPerNode * bitsPerElement;
        List<Long> ret = new ArrayList<>();
        if (nodesWithOrdinalZero.getElementValue(nodeIndex, 1, 1) != NO_ELEMENT) {
            // 0 indicates an "empty" element, so we fetch ordinal zeros from nodesWithOrdinalZero
            ret.add(NO_ELEMENT);
        }
        for (int offset = 0; offset < maxElementsPerNode; offset++) {
            long element = storage.getElementValue(bucketStart + offset * bitsPerElement,
                    bitsPerElement, elementMask);
            if (element == NO_ELEMENT) {
                break; // we have exhausted the elements at this index
            }
            ret.add(element);
        }
        return ret;
    }
Return a list of elements at the specified node index. The returned list may contain
duplicates.
This method not thread-safe - the caller must ensure that no one calls {@link #addElement}
concurrently with this method, but calling this method concurrently with itself is safe.

@param nodeIndex the node index
@return a list of element at the node index