/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main(String[] args) {
        GettingEmSafety safety = new GettingEmSafety();
        System.out.println(safety.getValues());
        safety.getValues().removeAll(safety.getValues());
        System.out.println(safety.getValues());
    }
}

class GettingEmSafety {
    private final Collection<String> values;

    public GettingEmSafety() {
        values = new ArrayList<>();
        values.add("First");
        values.add("Second");
    }

    private class MyCol extends ArrayList<String> {
        public MyCol(Collection c) {
            super(c);
        }

        @Override
        public boolean removeAll(Collection c) {
            return true;
        }
    }

    public Collection<String> getValues() {
        MyCol col = new MyCol(this.values);
        return col;
    }
}