Ошибка NullPointerException при реализации метода Iterator интерфейса Iterable

  import java.util.Iterator;

public class CarHashSet implements CarSet {

    private static final int INITIAL_CAPACITY = 16;                 
    private static final double LOAD_FACTOR = 0.75;  
    private int size = 0;                                          
    private Entry[] array = new Entry[INITIAL_CAPACITY];           

    @Override
    public boolean add(Car car) {                                 
        if (size >= (array.length * LOAD_FACTOR)) {  
            increaseArray();                                       
        }
        boolean added = add(car, array);                          
        if (added) {                                              
            size++;                                               
        }
        return added;                                              
    }
    
 private boolean add(Car car, Entry[] dst) {                  
        int position = getElementPosition(car, dst.length);     
        if (dst[position] == null) {                             
            Entry entry = new Entry(car, null);  
            dst[position] = entry;                               
            return true;
        } else {                    
            Entry existedElement = dst[position];                     
            while (true) {                                               
                if (existedElement.value.equals(car)) {                 
                    return false;
                } else if (existedElement.next == null) {       
                    existedElement.next = new Entry(car, null);         
                    return true;
                } else {                                               
                    existedElement = existedElement.next;                 
                }
            }
        }
    }

    @Override
    public boolean remove(Car car) {
        int position = getElementPosition(car, array.length);     
        if (array[position] == null) {                          
            return false;                                        

        Entry secondLast = array[position];                      
        Entry last = secondLast.next;  
        if (secondLast.value.equals(car)) {                   
            array[position] = last;  
            size--;                                              
            return true;

        while (last != null) {                                         
            if (last.value.equals(car)) {  
                secondLast.next = last.next;                         
                size--;
                return true;
            } else {                       
                secondLast = last;                                    
                last = last.next;
            }
        }
        return false;                                                 
    }

    @Override
    public boolean contains(Car car) {                           
        int position = getElementPosition(car, array.length);    
        if (array[position] == null) {                           
            return false;                                        
        }
        Entry secondLast = array[position];                    
        Entry last = secondLast.next; 
        if (secondLast.value.equals(car)) {                   
            return true;                                      
        }
        while (last != null) {                                      
            if (last.value.equals(car)) {                           
                return true;                                        
            } else {                   
                last = last.next;
            }
        }
        return false;                                                 
    }


    @Override
    public int size() {
        return size;
    }

    @Override
    public void clear() {
        array = new Entry[INITIAL_CAPACITY];                          
        size = 0;
    }

    @Override // интерфейс(Iterable)  
    public Iterator<Car> iterator() {                                     
        return new Iterator<Car>() {                                  
            
            int index = 0;                                       
            int arrayIndex = 0;                                       
            Entry entry;                                      

            @Override
            public boolean hasNext() {  
                return index < size;
            }

            @Override
            public Car next() {                                 
                while (array[arrayIndex] == null) {   
                    arrayIndex++;                               
                }
                if (entry == null) {              
                    entry = array[index];                       
                }
                Car result = entry.value;                        
                entry = entry.next;                            
                if (entry == null) {                             
                    arrayIndex++; // тогда нужно увеличить номер 
                }
                index++;                                       
                return result;                                
            }
        };
    }



    private void increaseArray() {            
        Entry[] newArray = new Entry[array.length * 2];                   
        for (Entry entry : array) {                                     
            Entry existedElement = entry;                              
            while (existedElement != null) {                           
                add(existedElement.value, newArray);                   
                existedElement = existedElement.next;                   
            }
        }
        array = newArray;                                        
    }

     
    private int getElementPosition(Car car, int arrayLength) {       
        return Math.abs(car.hashCode() % arrayLength);           
    }


    private static class Entry {            
        private Car value;                
        private Entry next;                

        public Entry(Car value, Entry next) {
            this.value = value;
            this.next = next;
        }
    }
}






    @Test
    public void testForeach() { 
        int index = 0;
        for (Car car : carCollection) {                               
            index++;
        }
        assertEquals(100, index);
    }

Cannot read field "value" because "this.entry" is null