Add missing isDebugEnabled guard in FrameworkServlet

Issue: SPR-8085

git-svn-id: https://src.springframework.org/svn/spring-framework/trunk@4517 50f2f4bb-b051-0410-bef5-90022cba6387

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/FrameworkServlet.java

@@ -874,11 +874,13 @@ public abstract class FrameworkServlet extends HttpServletBean {
 				logger.trace("Cleared thread-bound request context: " + request);
 			}
 
-			if (failureCause != null) {
+			if (logger.isDebugEnabled()) {
-				this.logger.debug("Could not complete request", failureCause);
+				if (failureCause != null) {
-			}
+					this.logger.debug("Could not complete request", failureCause);
-			else {
+				}
-				this.logger.debug("Successfully completed request");
+				else {
+					this.logger.debug("Successfully completed request");
+				}
 			}
 			if (this.publishEvents) {
 				// Whether or not we succeeded, publish an event.