Question 2 The following is an interrace for a class PriorityQueue: class PriorityQueue { } /* attributes */ int currentSize; // stores current number of elements in PQ FlightNode [] array; // array to store flight nodes, implements PQ int DEFAULT CAPACITY=2>>10; // maximum heap size /* methods */ void clear(); Boolean isEmpty(); Boolean add (FlightNode x); FlightNode remove (); void percolate Down (int hole); Create a class PriorityQueue and write code for the following 2.1 Encapsulate/hide each attribute by adding an appropriate modifier to its definition. 2.2 A default constructor 2.3 A loaded constructor 2.4 Accessor methods for each attribute 2.5 Mutator methods for each attribute 2.6 A method void clear () which empties the heap and resets the current Size attribute 2.7 A method Boolean isEmpty() which returns a Boolean value indicating whether the heap contains elements 2.8 A method Boolean add (FlightNode x) which adds a new element, x, of type FlightNode, to the heap in its correct position. This method should make use of a "percolate up" strategy. The return value indicates whether the element was added successfully. 2.9 A method FlightNode remove () which removes the element at the top of the heap and returns the element that was removed. This method should invoke percolate Down (int hole) to be defined in 2.10. 2.10 A method percolate Down (int hole) which restores the heap property after deletion by moving the hole to the outermost level of the heap.