我创建了两个类Content和Bucket。 Bucket包含一组Content对象，并通过public属性公开。但是，当我这样做，我收到错误：
Property cannot be declared public because its type uses an internal type
对于为什么会引发错误的任何想法？
您还必须声明Content类的访问级别public。
public class Content {
// some code
}
如documentation所述：
A public variable cannot be defined as having an internal or private
type,because the type might not be available everywhere that the
public variable is used.
默认情况下，类被声明为内部，因此您必须添加public关键字才能使其公开。
函数也存在类似的规则。
A function cannot have a higher access level than its parameter types and return type,because the function could be used in situations where its constituent types are not available to the surrounding code.
