@Nullable
    protected final Reference<K, V> getReference(@Nullable Object key, Restructure restructure) {
        int hash = getHash(key);
        return getSegmentForHash(hash).getReference(key, hash, restructure);
    }
Return a {link Reference} to the {link Entry} for the specified {@code key},
or {@code null} if not found.

@param key         the key (can be {@code null})
@param restructure types of restructure allowed during this call
@return the reference, or {@code null} if not found
analyzer/src/main/java/nl/basjes/parse/useragent/utils/springframework/util/ConcurrentReferenceHashMap.java