[GH-27] main build results in unstable build

[shinhyungyang]

This happens at unit test since #3007 was merged.

17916   TestConfigurationFactoryMethods > testCreationDefaultConfiguration FAILED
17917       java.lang.AssertionError: expected:<true> but was:<false>
17918           at org.junit.Assert.fail(Assert.java:89)
17919           at org.junit.Assert.failNotEquals(Assert.java:835)
17920           at org.junit.Assert.assertEquals(Assert.java:120)
17921           at org.junit.Assert.assertEquals(Assert.java:146)
17922           at kieker.test.monitoring.junit.core.configuration.TestConfigurationFactoryMethods.testCreationDefaultConfiguration(TestConfigurationFactoryMethods.java:145)
17923
17924   TestConfigurationFactoryMethods > testCreationfromFile STANDARD_OUT
17925       08:02:58.899 [Test worker] INFO  k.t.common.junit.AbstractKiekerTest - Executing test: kieker.test.monitoring.junit.core.configuration.TestConfigurationFactoryMethods.testCreationfromFile()
--
43076   TestConfigurationFactoryMethods > testCreationDefaultConfiguration FAILED
43077       java.lang.AssertionError: expected:<true> but was:<false>
43078           at org.junit.Assert.fail(Assert.java:89)
43079           at org.junit.Assert.failNotEquals(Assert.java:835)
43080           at org.junit.Assert.assertEquals(Assert.java:120)
43081           at org.junit.Assert.assertEquals(Assert.java:146)
43082           at kieker.test.monitoring.junit.core.configuration.TestConfigurationFactoryMethods.testCreationDefaultConfiguration(TestConfigurationFactoryMethods.java:145)
43083
43084   TestConfigurationFactoryMethods > testCreationfromFile STANDARD_OUT
43085       08:33:49.236 [Test worker] INFO  k.t.common.junit.AbstractKiekerTest - Executing test: kieker.test.monitoring.junit.core.configuration.TestConfigurationFactoryMethods.testCreationfromFile()