Add tests, add docu, use subpackage.

src/test/java/io/kokuwa/micronaut/logging/AbstractTest.java

@@ -0,0 +1,25 @@
+package io.kokuwa.micronaut.logging;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.MethodOrderer.Alphanumeric;
+import org.junit.jupiter.api.TestMethodOrder;
+import org.slf4j.MDC;
+
+import io.micronaut.test.annotation.MicronautTest;
+
+/**
+ * Base for tests regarding logging.
+ *
+ * @author Stephan Schnabel
+ */
+@MicronautTest
+@TestMethodOrder(Alphanumeric.class)
+public abstract class AbstractTest {
+
+	@BeforeEach
+	@AfterEach
+	void setUpMdc() {
+		MDC.clear();
+	}
+}