anchor.diff:  <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
  +<c:set var="categoryId" value="${not empty param.category ? '&category='.concat(param.category) : '' }"/>
   <nav aria-label="Page navigation">
       <ul class="pagination">
           <li>
               <c:if test="${movies.hasPreviousPage()}">
               <a
  -                href="${request.contextPath}?page=${movies.previousPage()}"
  +                href="${request.contextPath}?page=${movies.previousPage()}${categoryId}"
                   aria-label="Previous"
               >
                   <span aria-hidden="true">&laquo;</span>
  
positive.code:         <li>
              <c:if test="${movies.hasNextPage()}">
              <a
                  href="${request.contextPath}?page=${movies.nextPage()}"
                  aria-label="Next"
              >
                  <span aria-hidden="true">&raquo;</span>
  
negative.code:         </li>
          <c:forEach begin="1" end="${movies.pagesCount()}" varStatus="loop">
              <li>
                  <a href="${request.contextPath}?page=${loop.count}${categoryId}">
                      <c:out value="${loop.count}"/>
                  </a>
              </li>
  