Add test-case for unregistered custom fields

Unregistered custom fields should not be added to the `#cf` field.
Only fields explicitly configured in the config files are added there.

Author: KarstenSchnitter

cf-java-logging-support-log4j2/src/test/java/com/sap/hcp/cf/logging/common/TestCustomFields.java

@@ -29,6 +29,14 @@ public void testLogMessageWithCustomField() throws Exception {
 		assertThat(getCustomField(CUSTOM_FIELD_KEY), hasCustomField(CUSTOM_FIELD_KEY, SOME_VALUE, CUSTOM_FIELD_INDEX));
 	}
 
+	@Test
+	public void testCustomFieldWithoutRegistration() throws Exception {
+		LOGGER.info(TEST_MESSAGE, customField("ungregistered", SOME_VALUE));
+
+		assertThat(getField("ungregistered"), is(SOME_VALUE));
+		assertThat(getCustomField("unregistered"), is(nullValue()));
+	}
+
 	@Test
 	public void testCustomFieldAsPartOfMessage() throws Exception {
 		String messageWithPattern = TEST_MESSAGE + " {}";

cf-java-logging-support-logback/src/test/java/com/sap/hcp/cf/logging/common/TestCustomFields.java

@@ -29,6 +29,14 @@ public void testLogMessageWithCustomField() throws Exception {
 		assertThat(getCustomField(CUSTOM_FIELD_KEY), hasCustomField(CUSTOM_FIELD_KEY, SOME_VALUE, CUSTOM_FIELD_INDEX));
 	}
 
+	@Test
+	public void testCustomFieldWithoutRegistration() throws Exception {
+		LOGGER.info(TEST_MESSAGE, customField("ungregistered", SOME_VALUE));
+
+		assertThat(getField("ungregistered"), is(SOME_VALUE));
+		assertThat(getCustomField("unregistered"), is(nullValue()));
+	}
+
 	@Test
 	public void testCustomFieldAsPartOfMessage() throws Exception {
 		String messageWithPattern = TEST_MESSAGE + " {}";