java.lang.NoClassDefFoundError: Could not initialize class org.apache.commons.text.StringEscapeUtils

Question

I am writing a character filter function, using commons-text-1.6.jar.
The log function is okay, but then this error shows up:

java.lang.NoClassDefFoundError: Could not initialize class org.apache.commons.text.StringEscapeUtils
    cc.openhome.web.EscapeWrapper.getParameter(EscapeWrapper.java:15)
    cc.openhome.controller.Login.doPost(Login.java:30)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
    cc.openhome.web.EscapeFilter.doFilter(EscapeFilter.java:16)

Code:

package cc.openhome.web;

import org.apache.commons.text.StringEscapeUtils;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrappe

public class EscapeWrapper extends HttpServletRequestWrapper {
    public EscapeWrapper(HttpServletRequest req){enter code here
        super(req);
    }

    public String getParameter(String name){
        String value = getRequest().getParameter(name);
        return StringEscapeUtils.escapeHtml4(value);
    }
}