Sorry I have not noticed that you are using github guava-master branch code , I have looked into my game that is built without Gradle & found that I am using guava26jre.jar , it’s not easy to find a guava jar file so this is the link🙂
https://repo1.maven.org/maven2/com/google/guava/guava/26.0-jre/guava-26.0-jre.jar