maven javadoc Illegal package name error

I get the following error when I run mvn javadoc:javadoc

[ERROR] Exit code: 1 - javadoc: error - Illegal package name: "edu.princeton.cs.1-Fundamentals.1-1-BasicProgModel"

The reason I pretty clear but I don't know how to solve it.

This is my src file structure in the folder src/main/java/edu/princeton/cs/.

├── 1-Fundamentals
│   ├── 1-1-BasicProgModel
│   ├── 1-2-DataAbstraction
│   ├── 1-3-BagsQueuesStacks
│   ├── 1-4-AnalysisOfAlgorithms
│   └── 1-5-UnionFind
├── 2-Sorting
│   ├── 2-1-ElementarySorts
│   ├── 2-2-Mergesort

In each directory, the java code contains package edu.princeton.cs.algs4;

That means the folder name is not the package name. However, the javadoc mistakenly think the folder name is the package name.

How can I let maven know that there are no package like edu.princeton.cs.1-Fundamentals.1-1-BasicProgModel