code: public int incrementCount(E key, int count) {
      if (tempMInteger == null) {
        tempMInteger = new MutableInteger();
      }
  
      MutableInteger oldMInteger = map.put(key, tempMInteger);
      totalCount += count;
      if (oldMInteger != null) {
        count += oldMInteger.intValue();
      }
      tempMInteger.set(count);
      tempMInteger = oldMInteger;
  
      return count;
    }
docs: Adds the given count to the current count for the given key. If the key
  hasn't been seen before, it is assumed to have count 0, and thus this
  method will set its count to the given amount. Negative increments are
  equivalent to calling <tt>decrementCount</tt>.
  <p/>
  To more conveniently increment the count by 1, use
  {@link #incrementCount(Object)}.
  <p/>
  To set a count to a specific value instead of incrementing it, use
  {@link #setCount(Object,int)}.