public void insert(long key, Posting posting) {
            dictionaryBuilder.computeIfAbsent(key, (k) -> new ArrayList<>()).add(posting);
            ++entryCount;
        }
Inserts an object with an id for a key.
@param key Key to map from
@param posting Entry for the posting list
predicate-search/src/main/java/com/yahoo/search/predicate/index/SimpleIndex.java