Chart.js значение на гистограмме не исчезает при отмене выбора

 /** Comparing two or more variables. Here the two items are compared and it will return a boolean true or false.
 * 
 * @return equals
 */
public boolean equals(Object item)
{
    String emp1 = this.toString();
    String emp2 = item.toString();
    return emp1.equals(emp2);
}

@Override
//In case you have more than one variable.
public String toString()
{
    return a + b;
}

// a and b represent the variables to display.