6. As described in class, a stack can be implemented using a sequentially linked structure. The Stack interface and the exception classes NoItemException and NoSpaceException have been defined as part of the Collections package as discussed in class. and the exception classes Noons package as As part of the package Collections, write the class header and instance variables for the class LnkStack that implements Stack as a sequentially-linked structure a. b. Write the constructor that creates a new empty stack public LnkStack b. Write the method that adds item to the stack. public void push E item) Write the method that removes the top item from the stack. c. public E pop ) 6. As described in class, a stack can be implemented using a sequentially linked structure. The Stack interface and the exception classes NoItemException and NoSpaceException have been defined as part of the Collections package as discussed in class. and the exception classes Noons package as As part of the package Collections, write the class header and instance variables for the class LnkStack that implements Stack as a sequentially-linked structure a. b. Write the constructor that creates a new empty stack public LnkStack b. Write the method that adds item to the stack. public void push E item) Write the method that removes the top item from the stack. c. public E pop )