JAXB -复合模式和@XmlValue

Question

继JAXB和复合模式之后，我设法映射：

<precondition>
    <or>
        <and>
            <just><query>foo</query></just>
            <just><query>bar</query></just>
        </and>
        <just><query>baz</query></just>
    </or>
</precondition>

但我想绘制：

<precondition>
    <or>
        <and>
            <query>foo</query>
            <query>bar</query>
        </and>
        <query>baz</query>
    </or>
</precondition>

我的JAXB类层次结构如下：

@XmlRootElement
@XmlSeeAlso({SimplePreconditionQuery.class, CompoundAndPreconditionQuery.class, CompoundOrPreconditionQuery.class})
public abstract class PreconditionQuery {
    // JAXB does not deal with interfaces by default >:(
}

有几种类型的查询:

@XmlSeeAlso(PreconditionQuery.class)
@XmlRootElement(name = "just")
public class SimplePreconditionQuery extends PreconditionQuery {

    private String query;

    @XmlElement(name = "query")
    public String getQuery() {
        return query;
    }

    public void setQuery(String query) {
        this.query = query;
    }
}

复合词(和/或)非常相似:

@XmlSeeAlso(PreconditionQuery.class)
@XmlRootElement(name = "and")
public class CompoundAndPreconditionQuery extends PreconditionQuery {

    private Collection<PreconditionQuery> preconditionQueries = newArrayList();

    @XmlElementRef(name = "query")
    public Collection<PreconditionQuery> getPreconditionQueries() {
        return preconditionQueries;
    }

    public void setPreconditionQueries(Collection<PreconditionQuery> preconditionQueries) {
        this.preconditionQueries = preconditionQueries;
    }
}

和封闭bean:

public class Precondition {

    private PreconditionQuery query;

    @XmlElementRef(required = true)
    public PreconditionQuery getQuery() {
        return query;
    }

    public void setQuery(PreconditionQuery query) {
        this.query = query;
    }
}

JAXB不允许我只在SimplePreoditionQuery上映射@XmlValue。为什么以及有什么替代方案？