示例

public class Outer {

private final class Inner1 {

private final class Inner2 {

private final class Inner3 {

}
}
}

}

解决方案
将嵌套的内部类移到最外部的内部类级别。

public class Outer {

private final class Inner1 {}

private final class Inner2 {}

private final class Inner3 {}

}