请教高手如何解决该问题: signer information does not match signer information
严重: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in ServletContext resource [/WEB-INF/applicationContext.xml]: Invocation of init method failed; nested exception is java.lang.SecurityException: class "org.apache.commons.collections.SequencedHashMap"'s signer information does not match signer information of other classes in the same package
Caused by: java.lang.SecurityException: class "org.apache.commons.collections.SequencedHashMap"'s signer information does not match signer information of other classes in the same package

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public class Admin implements java.io.Serializable {
private int adminid;
private String name;
private String password;
private Set courses=new HashSet();
private Set Teachers=new HashSet();
private Set Students=new HashSet();
...



------解决方案--------------------
你把类的代码发上来