private void init(int initCapacity)
        {
            // assert (initCapacity & -initCapacity) == initCapacity; // power of 2
            // assert initCapacity >= MINIMUM_CAPACITY;
            // assert initCapacity <= MAXIMUM_CAPACITY;

            threshold = (initCapacity * 2) / 3;
            table = new Object[2 * initCapacity];
        }
Initializes object to be an empty map with the specified initial capacity, which is assumed to be a power of
two between MINIMUM_CAPACITY and MAXIMUM_CAPACITY inclusive.
protostuff-core/src/main/java/io/protostuff/GraphProtostuffOutput.java