Why am I getting this error if commons-lang jar is added to referenced libraries

I downloaded java-faker

http://ift.tt/1EPcz6l

I unzipped it, did maven package and in the target folder I got the jar for faker and added it to the build path. Selenium comes with commons-lang so i don't know what's causing the problem.

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/lang/math/RandomUtils
        at com.github.javafaker.service.RandomService.<init>(RandomService.java:14)
        at com.github.javafaker.Faker.<init>(Faker.java:40)
        at com.github.javafaker.Faker.<init>(Faker.java:32)
        at com.github.javafaker.Faker.<init>(Faker.java:28)
        at FirstProgram.main(FirstProgram.java:12)
    Caused by: java.lang.ClassNotFoundException: org.apache.commons.lang.math.RandomUtils
        at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
        ... 5 more