public void setSecurityManager(SecurityManager securityManager) {
        this.securityManager = securityManager;
    }
Sets the application {@code SecurityManager} instance to be used by the constructed Shiro Filter.  This is a
required property - failure to set it will throw an initialization exception.

@param securityManager the application {@code SecurityManager} instance to be used by the constructed Shiro Filter.
support/spring/src/main/java/org/apache/shiro/spring/web/ShiroFilterFactoryBean.java