import com.sun.tools.javadoc.Start; //导入依赖的package包/类
public Boolean call() {
    if (!used.getAndSet(true)) {
        initContext();
        Start jdoc = new Start(context);
        try {
            return jdoc.begin(docletClass, options, fileObjects);
        } catch (ClientCodeException e) {
            throw new RuntimeException(e.getCause());
        }
    } else {
        throw new IllegalStateException("multiple calls to method 'call'");
    }
}