import ru.org.linux.util.ServletParameterException;
import ru.org.linux.util.ServletParameterMissingException;
import javax.annotation.Nullable;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
<BUG>import java.net.URLEncoder;
import java.util.*;
</BUG>
@Controller
public class TopicListController {

import ru.org.linux.util.ServletParameterException;
import ru.org.linux.util.ServletParameterMissingException;
import javax.annotation.Nullable;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.net.URLEncoder;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
@Controller
public class TopicListController {
