JSP Expression Language not rendering properties from JavaBean

Well, this error is surely caused by making some sort of mistake done by me. Here is my code below.

The servlet:

package Servlets;

// import statements

public class AdminResource extends HttpServlet {

    List<userList> users = new ArrayList<>();

    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
                                throws ServletException, IOException {
        Database db = (Database) getServletContext().getAttribute("db");
        String sql = "select * from TAHMID_NIPS.GROUPS";
        ResultSet rs;
        try {
            rs = db.runSql(sql);
            // int i = 0;
            while (rs.next()) {
                userList user = new userList(rs.getString("USERNAME"), rs.getString("GROUPID"));
                users.add(user);
                /* used a printWriter here to access the bean in the servlet
                out.println(users.get(i).getUserName());
                out.println(users.get(i).getGroupID());
                i++;
                */
            }
            request.setAttribute("users", users);
            request.getRequestDispatcher("userList.jsp").forward(request, response);
        } catch(SQLException ex){}
    }

    // doGet(), doPost(),  getServletInfo() methods..
}

The JavaBean class::

public class userList {

    private String GroupID;
    private String UserName;

    public userList(String GroupID, String UserName){
        this.GroupID = GroupID;
        this.UserName = UserName;
    }

    public String getGroupID() {
        return GroupID;
    }

    public void setGroupID(String GroupID) {
        this.GroupID = GroupID;
    }

    public String getUserName() {
        return UserName;
    }

    public void setUserName(String UserName) {
        this.UserName = UserName;
    }
}

The dispatched JSP view:

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@ taglib prefix="c"  uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>JSP Page</title>
</head>
<body>
    <h1>These are the users in the database!</h1><br>
    <c:forEach var="iterator" items="${users}">
        <c:out value="${iterator.UserName}"/> <br>
    </c:forEach>
</body>
</html>

The database URL, passwords and other required information are declared in the web.xml file and a contextListener class is implemented. The app was working fine when data was being shown in the servlet. But as we are MVC fans, problem started when I tried to access the bean with EL. The fields were unable to be accessed.

About the database:
Here is a table named Groups with two fields: UserName, GroupID. But none of them are being shown in the JSP view.

The problem might have occurred in the EL in the JSP view. Experts, please help.