Struts2 debug = browser不捕获动作类变量中的url参数？

Test action data=hello

public class ActionTest extends ActionSupport {

private static final long serialVersionUID = -2606731098320589210L;
private String data;

public String getData() {
    return data;
}

public void setData(String data) {
    this.data = data;
}

@Action(value = "mytestaction")
public String execute() {
    System.out.println("Test action data="+data);
    return SUCCESS;
}
}

Test action data=null

data

<actionErrors /> 
<actionMessages /> 
<class>class com.ycs.fe.actions.ActionTest</class> 
<data>hello</data> 
<errorMessages /> 
<errors /> 
<fieldErrors /> 

#action.data =>shows hello

#parameters.data[0] => shows hello