Run mvn test to make sure you have JDK 8 and all dependencies in place.
Run Lesson00_HelloWorldTest.java from your favourite IDE and make sure it compiles and passes.
If you see this error message during maven build:
[INFO] BUILD FAILURE
...
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project lazyseq:
Fatal error compiling: invalid target release: 1.8 -> [Help 1]
it means you are not compiling using Java 8. Download JDK 8 with lambda support and let maven use it:
$ export JAVA_HOME=/path/to/jdk8