To reproduce the bug, execute
mvn clean test
The test class ERRORControllerTes contains the tests (nested classes) that reproduce the error. Notice that the nested classes are only to ensure the order of the tests. The error can be reproduced as well if you execute all tests in expanded package following the order: FirstControllerTest, SecondControllerTest and ThirdControllerTest.
The test class OKControllerTest contains version which does not fail