If you use this example result type

<result type="chain" name="input.show">
                <param name="actionName">User!list</param>
                <param name="namespace">/admin</param>
            </result>

You get an Exception.

The solution is in com.opensymphony.xwork.DefaultActionProxy.java

protected DefaultActionProxy(String namespace, String actionName, Map extraContext, boolean executeResult, boolean cleanupContext) throws Exception {
        this.cleanupContext = cleanupContext;
        if (LOG.isDebugEnabled()) {
            LOG.debug("Creating an DefaultActionProxy for namespace " + namespace + " and action name " + actionName);
        }

// START PATCH

int posExcl = actionName.indexOf("!");
        if (posExcl > -1) {
            this.method = actionName.substring(posExcl+1);
            actionName = actionName.substring(0, posExcl);
        }

// END PATCH

this.actionName = actionName;
        this.namespace = namespace;
        this.executeResult = executeResult;
        this.extraContext = extraContext;