import com.sun.tools.internal.xjc.reader.xmlschema.bindinfo.BIXSubstitutable; //导入依赖的package包/类
protected RawTypeSet.Mode canBeType(RawTypeSet parent) {
    // if element substitution can occur, no way it can be mapped to a list of types
    if(decl.getSubstitutables().size()>1)
        return RawTypeSet.Mode.MUST_BE_REFERENCE;
    // BIXSubstitutable also simulates this effect. Useful for separate compilation
    BIXSubstitutable subst = builder.getBindInfo(decl).get(BIXSubstitutable.class);
    if(subst!=null) {
        subst.markAsAcknowledged();
        return RawTypeSet.Mode.MUST_BE_REFERENCE;
    }

    // we have no place to put an adater if this thing maps to a type
    CElementPropertyInfo p = target.getProperty();
    // if we have an adapter or IDness, which requires special
    // annotation, and there's more than one element,
    // we have no place to put the special annotation, so we need JAXBElement.
    if((parent.refs.size()>1 || !parent.mul.isAtMostOnce()) && p.id()!=ID.NONE)
        return RawTypeSet.Mode.MUST_BE_REFERENCE;
    if(parent.refs.size() > 1 && p.getAdapter() != null)
        return RawTypeSet.Mode.MUST_BE_REFERENCE;

    if(target.hasClass())
        // if the CElementInfo was explicitly bound to a class (which happen if and only if
        // the user requested so, then map that to reference property so that the user sees a class
        return RawTypeSet.Mode.CAN_BE_TYPEREF;
    else
        return RawTypeSet.Mode.SHOULD_BE_TYPEREF;
}