Debug-level log entry for any Jackson exception during canConvert

Issue: SPR-15582

spring-messaging/src/main/java/org/springframework/messaging/converter/MappingJackson2MessageConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -178,10 +178,20 @@ public class MappingJackson2MessageConverter extends AbstractMessageConverter {
 	 * @since 4.3
 	 */
 	protected void logWarningIfNecessary(Type type, Throwable cause) {
-		if (cause != null && !(cause instanceof JsonMappingException && cause.getMessage().startsWith("Can not find"))) {
+		if (cause == null) {
+			return;
+		}
+
+		boolean debugLevel = (cause instanceof JsonMappingException &&
+				cause.getMessage().startsWith("Can not find"));
+
+		if (debugLevel ? logger.isDebugEnabled() : logger.isWarnEnabled()) {
 			String msg = "Failed to evaluate Jackson " + (type instanceof JavaType ? "de" : "") +
 					"serialization for type [" + type + "]";
-			if (logger.isDebugEnabled()) {
+			if (debugLevel) {
+				logger.debug(msg, cause);
+			}
+			else if (logger.isDebugEnabled()) {
 				logger.warn(msg, cause);
 			}
 			else {

spring-web/src/main/java/org/springframework/http/converter/json/AbstractJackson2HttpMessageConverter.java

@@ -191,10 +191,20 @@ public abstract class AbstractJackson2HttpMessageConverter extends AbstractGener
 	 * @since 4.3
 	 */
 	protected void logWarningIfNecessary(Type type, Throwable cause) {
-		if (cause != null && !(cause instanceof JsonMappingException && cause.getMessage().startsWith("Can not find"))) {
+		if (cause == null) {
+			return;
+		}
+
+		boolean debugLevel = (cause instanceof JsonMappingException &&
+				cause.getMessage().startsWith("Can not find"));
+
+		if (debugLevel ? logger.isDebugEnabled() : logger.isWarnEnabled()) {
 			String msg = "Failed to evaluate Jackson " + (type instanceof JavaType ? "de" : "") +
 					"serialization for type [" + type + "]";
-			if (logger.isDebugEnabled()) {
+			if (debugLevel) {
+				logger.debug(msg, cause);
+			}
+			else if (logger.isDebugEnabled()) {
 				logger.warn(msg, cause);
 			}
 			else {