The following class represents a $3$d shape using an array of $3$dPoints. It is intended to be immutable. Assume the $3$dPoint class is immutable.

Some of these functions, by their nature, make the class mutable and should be removed completely to make it immutable.

Some others might make the class mutable, but it is possible to make them safe by implementing them carefully.

Others are mostly safe in an immutable class.

Determine which functions should be removed, which must be carefully implemented, and which are safe.

public class $3$dShape$\{$