SLING-3048 - Filter to populate SLF4J MDC with request details

Filter would only be enabled if explicitly configured

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1594788 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/src/main/java/org/apache/sling/extensions/mdc/internal/MDCInsertingFilter.java b/src/main/java/org/apache/sling/extensions/mdc/internal/MDCInsertingFilter.java
index fcb8145..5c8c3a8 100644
--- a/src/main/java/org/apache/sling/extensions/mdc/internal/MDCInsertingFilter.java
+++ b/src/main/java/org/apache/sling/extensions/mdc/internal/MDCInsertingFilter.java
@@ -20,6 +20,7 @@
 
 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.ConfigurationPolicy;
 import org.apache.felix.scr.annotations.Deactivate;
 import org.apache.felix.scr.annotations.Modified;
 import org.apache.felix.scr.annotations.Property;
@@ -52,7 +53,9 @@
 @Service
 @Component(metatype = true,
         label="%mdc.label",
-        description = "%mdc.description")
+        description = "%mdc.description",
+        policy = ConfigurationPolicy.REQUIRE
+)
 @Property(name = "pattern",value = "/.*", propertyPrivate = true)
 /**
  * Filter is based on ch.qos.logback.classic.helpers.MDCInsertingServletFilter