Byte layout:
Header
0 to 1 : the MSB is a boolean flag for isLeaf, the next 15 bits represent the number of children of a node
Body
2 to 2 + numDims * Floats.BYTES : minCoordinates
2 + numDims * Floats.BYTES to 2 + 2 * numDims * Floats.BYTES : maxCoordinates
concise set
rest (children) : Every 4 bytes is storing an offset representing the position of a child.