EDIT

import java.io.IOException;

import java.util.ArrayList;

import java.util.Collection;

import javax.servlet.http.HttpServletResponse;

import org.springframework.web.bind.annotation.RequestMapping;

import eu.etaxonomy.cdm.api.service.pager.Pager;

import eu.etaxonomy.cdm.api.service.pager.impl.DefaultPagerImpl;

    protected <T extends CdmBase> Pager<T> pagerForSubCollectionOf(Collection<T> c, Integer pageNumber, Integer pageSize, HttpServletResponse response) throws IOException {

        PagerParameters pagerParameters = new PagerParameters(pageSize, pageNumber);

        pagerParameters.normalizeAndValidate(response);

        int subCollectionStart = pagerParameters.getPageIndex() * pagerParameters.getPageSize();

        List<T> sub_c = subCollection(c, subCollectionStart, pagerParameters.getPageSize());

        Pager<T> p = new DefaultPagerImpl<>(pageNumber, c.size(), pagerParameters.getPageSize(), sub_c);

        return p;

    }

    protected <E> List<E> subCollection(Collection<? extends E> c, Integer start, Integer length) {

        List<E> sub_c = new ArrayList<E>(length);

        if(c.size() > length){

            E[] a = (E[]) c.toArray();

            for(int i = start; i < start + length; i++){

                sub_c.add(a[i]);

            }

        } else {

            sub_c.addAll(c);

        }

        return sub_c;

    }