diff --git a/spring-web/src/main/java/org/springframework/web/method/annotation/MapMethodProcessor.java b/spring-web/src/main/java/org/springframework/web/method/annotation/MapMethodProcessor.java
index fa5cfc467754..4f1480b56743 100644
--- a/spring-web/src/main/java/org/springframework/web/method/annotation/MapMethodProcessor.java
+++ b/spring-web/src/main/java/org/springframework/web/method/annotation/MapMethodProcessor.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -42,8 +42,8 @@ public class MapMethodProcessor implements HandlerMethodArgumentResolver, Handle
 
 	@Override
 	public boolean supportsParameter(MethodParameter parameter) {
-		return Map.class.isAssignableFrom(parameter.getParameterType()) &&
-				parameter.getParameterAnnotations().length == 0;
+		return (Map.class.isAssignableFrom(parameter.getParameterType()) &&
+				parameter.getParameterAnnotations().length == 0);
 	}
 
 	@Override
@@ -70,8 +70,8 @@ public void handleReturnValue(@Nullable Object returnValue, MethodParameter retu
 		}
 		else if (returnValue != null) {
 			// should not happen
-			throw new UnsupportedOperationException("Unexpected return type: " +
-					returnType.getParameterType().getName() + " in method: " + returnType.getMethod());
+			throw new UnsupportedOperationException("Unexpected return type [" +
+					returnType.getParameterType().getName() + "] in method: " + returnType.getMethod());
 		}
 	}
 
diff --git a/spring-web/src/main/java/org/springframework/web/method/annotation/ModelMethodProcessor.java b/spring-web/src/main/java/org/springframework/web/method/annotation/ModelMethodProcessor.java
index 52a2756ac185..3915259ae7e7 100644
--- a/spring-web/src/main/java/org/springframework/web/method/annotation/ModelMethodProcessor.java
+++ b/spring-web/src/main/java/org/springframework/web/method/annotation/ModelMethodProcessor.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -70,8 +70,8 @@ else if (returnValue instanceof Model) {
 		}
 		else {
 			// should not happen
-			throw new UnsupportedOperationException("Unexpected return type: " +
-					returnType.getParameterType().getName() + " in method: " + returnType.getMethod());
+			throw new UnsupportedOperationException("Unexpected return type [" +
+					returnType.getParameterType().getName() + "] in method: " + returnType.getMethod());
 		}
 	}
 
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/PrincipalMethodArgumentResolver.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/PrincipalMethodArgumentResolver.java
index 751e3e743b05..dff70178eac6 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/PrincipalMethodArgumentResolver.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/PrincipalMethodArgumentResolver.java
@@ -38,29 +38,24 @@
  */
 public class PrincipalMethodArgumentResolver implements HandlerMethodArgumentResolver {
 
-
 	@Override
 	public boolean supportsParameter(MethodParameter parameter) {
-		Class<?> paramType = parameter.getParameterType();
-		return Principal.class.isAssignableFrom(paramType);
+		return Principal.class.isAssignableFrom(parameter.getParameterType());
 	}
 
 	@Override
 	public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
 			NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {
 
-		Class<?> paramType = parameter.getParameterType();
-
 		HttpServletRequest request = webRequest.getNativeRequest(HttpServletRequest.class);
 		if (request == null) {
-			throw new IllegalStateException(
-					"Current request is not of type [HttpServletRequest]: " + webRequest);
+			throw new IllegalStateException("Current request is not of type HttpServletRequest: " + webRequest);
 		}
 
 		Principal principal = request.getUserPrincipal();
-		if (principal != null && !paramType.isInstance(principal)) {
-			throw new IllegalStateException(
-					"Current user principal is not of type [" + paramType.getName() + "]: " + principal);
+		if (principal != null && !parameter.getParameterType().isInstance(principal)) {
+			throw new IllegalStateException("Current user principal is not of type [" +
+					parameter.getParameterType().getName() + "]: " + principal);
 		}
 
 		return principal;