How to set a txt-file so that it can be used internally in the .jar file?

Question

I have a library that I want to upload to maven central and use it in various projects. I am using a text file for better entropy for cryptography (diceware).

Now the problem is that even though maven says this file should be found if referenced to be in src/main/resources/neededfile.txt, however I am having a FNF exception.

How should I reference to the file so that it can always find it internally in the library ?

 try {
             f = new File("src/main/resources/diceware.txt");
            if (f.exists() && !f.isDirectory()) {
                file = f;
            }else {
                f = new File("src/main/java/io/recheck/client/diceware.txt");
                if (f.exists() && !f.isDirectory()) {
                    file = f;
                }else {
                    f = new File("diceware.txt");
                    file = f;
                   }
            }