Fix test in Maven run

There is pre-existing state in the MDC from other test-cases.
This state is reset at the start of each test-case.

Signed-off-by: Karsten Schnitter <k.schnitter@sap.com>

Author: KarstenSchnitter

cf-java-logging-support-core/src/test/java/com/sap/hcp/cf/logging/common/request/HttpHeadersTest.java

@@ -7,15 +7,21 @@
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.nullValue;
 
-import org.hamcrest.MatcherAssert;
-import org.junit.Assert;
+import org.junit.Before;
 import org.junit.Test;
 
 import com.sap.hcp.cf.logging.common.Defaults;
 import com.sap.hcp.cf.logging.common.Fields;
+import com.sap.hcp.cf.logging.common.LogContext;
 
 public class HttpHeadersTest {
 
+    @Before
+    public void resetLogContext() {
+        LogContext.resetContextFields();
+        HttpHeaders.propagated().stream().map(HttpHeader::getField).forEach(LogContext::remove);
+    }
+
     @Test
     public void hasCorrectNumberOfTypes() throws Exception {
         assertThat(HttpHeaders.values().length, is(equalTo(7)));