XmlJavaxFormat.java 文件源码

private Message.Builder createSubBuilder(Message.Builder builder,
        FieldDescriptor field, 
        ExtensionRegistry.ExtensionInfo extension) {

    Message.Builder subBuilder;
    if (extension == null) {
        subBuilder = builder.newBuilderForField(field);
    } else {
        subBuilder = extension.defaultInstance.newBuilderForType();
    }
    return subBuilder;
}