Cannot locate the chosen Objectfactory implementation:spring

Error message:

caused By:cannot Locate the chosen objectfactory implementation:spring-[Unknown location]
At Org.apache.struts2.config.AbstractBeanSelectionProvider.alias (abstractbeanselectionprovider.java:74)
At Org.apache.struts2.config.AbstractBeanSelectionProvider.alias (abstractbeanselectionprovider.java:45)
At Org.apache.struts2.config.DefaultBeanSelectionProvider.register (defaultbeanselectionprovider.java:363)
At Com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer (defaultconfiguration.java:240)
At Com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration (configurationmanager.java:67)
... More

Background:

Introducing struts basic Required Packages:
Commons-lang3-3.2.jar
Commons-fileupload-1.3.1.jar
Commons-io-2.2.jar
Freemarker-2.3.22.jar
Javassist-3.11.0.ga.jar
Ognl-3.0.6.jar
Struts2-core-2.3.24.1.jar
Xwork-core-2.3.24.1.jar

Introducing the Spring-web Package:
Aopalliance-1.0.jar
Commons-logging-1.1.1.jar
Spring-aop-4.2.4.release.jar
Spring-beans-4.2.4.release.jar
Spring-context-4.2.4.release.jar
Spring-core-4.2.4.release.jar
Spring-expression-4.2.4.release.jar
Spring-web-4.2.4.release.jar

Struts.xml

<?XML version= "1.0" encoding= "UTF-8"?><!DOCTYPE struts Public "-//apache software foundation//dtd struts Configuration 2.3//en" "Http://struts.apache.or G/dtds/struts-2.3.dtd "><Struts>......<!--Specifies that spring is responsible for the creation of the Action object -    <constantname= "Struts.objectfactory"value= "Spring" />......</Struts>

The reason for this error is that a jar package is missing:
Struts2-spring-plugin-2.3.15.1.jar It's a jar that integrates struts and spring

Cannot locate the chosen Objectfactory implementation:spring