为什么wsimport不保留我的模型类的toString()方法呢？所以我在我的Web服务中有这个模型类：

package webservice;
public class Book {
    private String title;
    private int pages;
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public int getPages() {
        return pages;
    }
    public void setPages(int pages) {
        this.pages = pages;
    }
    @Override
    public String toString() {
        return "Book [title=" + title + ", pages=" + pages + "]";
    }
}

现在我想为WS客户机生成必要的工件：
wsimport -keep http://localhost:8080/LibraryWs/BookWebServiceService?wsdl
并得到结果类：

package webservice;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlType;

/**
 * <p>Java class for book complex type.
 * 
 * <p>The following schema fragment specifies the expected content contained within this class.
 * 
 * <pre>
 * &lt;complexType name="book">
 *   &lt;complexContent>
 *     &lt;restriction base="{http://www.w3.org/2001/XMLSchema}anyType">
 *       &lt;sequence>
 *         &lt;element name="pages" type="{http://www.w3.org/2001/XMLSchema}int"/>
 *         &lt;element name="title" type="{http://www.w3.org/2001/XMLSchema}string" minOccurs="0"/>
 *       &lt;/sequence>
 *     &lt;/restriction>
 *   &lt;/complexContent>
 * &lt;/complexType>
 * </pre>
 * 
 * 
 */
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "book", propOrder = {
    "pages",
    "title"
})
public class Book {

    protected int pages;
    protected String title;

    /**
     * Gets the value of the pages property.
     * 
     */
    public int getPages() {
        return pages;
    }

    /**
     * Sets the value of the pages property.
     * 
     */
    public void setPages(int value) {
        this.pages = value;
    }

    /**
     * Gets the value of the title property.
     * 
     * @return
     *     possible object is
     *     {@link String }
     *     
     */
    public String getTitle() {
        return title;
    }

    /**
     * Sets the value of the title property.
     * 
     * @param value
     *     allowed object is
     *     {@link String }
     *     
     */
    public void setTitle(String value) {
        this.title = value;
    }
}

所以没有toString：）我在哪里可以找到关于这个行为的规范，或者我如何让jax-ws在我的WSDL中显式地包含这个方法？谢谢。