code: public long serializedSize(BloomFilter bf, TypeSizes typeSizes)
      {
          int size = typeSizes.sizeof(bf.hashCount); // hash count
          size += bf.bitset.serializedSize(typeSizes);
          return size;
      }
docs: Calculates a serialized size of the given Bloom Filter
  @see org.apache.cassandra.io.ISerializer#serialize(Object, org.apache.cassandra.io.util.DataOutputPlus)
  
  @param bf Bloom filter to calculate serialized size
  
  @return serialized size of the given bloom filter