In the kazurayam21 branch, the sample code of the Chapter9 "File Download" section explains several approaches where to locate the output files from the test cases.
based on the User's home directory
https://github.com/kazurayam/selenium-webdriver-java/blob/kazurayam21/selenium-webdriver-junit4/src/test/java/io/github/bonigarcia/webdriver/junit4/ch09/download/DownloadChromeJUnit4Test.java
targetFolder = new File(System.getProperty("user.home"), "Downloads");
based on the Current Working Directory
https://github.com/kazurayam/selenium-webdriver-java/blob/kazurayam21/selenium-webdriver-junit4/src/test/java/io/github/bonigarcia/webdriver/junit4/ch09/download/DownloadFirefoxJUnit4Test.java
targetFolder = new File(".");
and
https://github.com/kazurayam/selenium-webdriver-java/blob/kazurayam21/selenium-webdriver-junit4/src/test/java/io/github/bonigarcia/webdriver/junit4/ch09/download/DownloadHttpClientJUnit4Test.java
...
File pngFile = new File(".", "webdrivermanager.png");
...
File pdfFile = new File(".", "webdrivermanager.pdf");
...
The new File(".") means the Current Working Directory, which is equal to System.getProperty("user.dir"). The document wrotes:
We use the local project folder.
However, this is not necessarily right. As I explained in the #8, The Current Working Directory is NOT necessarily equal to the local project folder.