Allow explicitly declared null in providedArgs when no argument resolver matches

spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/ExceptionHandlerTests.java

@@ -29,6 +29,7 @@
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.bind.annotation.RestControllerAdvice;
+import org.springframework.web.method.HandlerMethod;
 
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.forwardedUrl;
@@ -62,6 +63,14 @@ void globalExceptionHandlerMethod() throws Exception {
 				.andExpect(status().isOk())
 				.andExpect(forwardedUrl("globalErrorView"));
 		}
+
+		@Test
+		void nullHandlerMethod() throws Exception {
+			standaloneSetup(new PersonController()).setControllerAdvice(new GlobalExceptionHandler()).build()
+				.perform(get("/invalid"))
+				.andExpect(status().isOk())
+				.andExpect(forwardedUrl("null handlerMethod exception"));
+		}
 	}
 
 
@@ -92,6 +101,14 @@ private static class GlobalExceptionHandler {
 		String handleException(IllegalStateException exception) {
 			return "globalErrorView";
 		}
+
+		@ExceptionHandler(Exception.class)
+		String handleAllExceptions(IllegalStateException exception, HandlerMethod handlerMethod) {
+			if (handlerMethod == null) {
+				return "null handlerMethod exception";
+			}
+			return "simulated exception";
+		}
 	}
 
 

spring-web/src/main/java/org/springframework/web/method/support/InvocableHandlerMethod.java

@@ -218,6 +218,10 @@ public void setMethodValidator(@Nullable MethodValidator methodValidator) {
 				continue;
 			}
 			if (!this.resolvers.supportsParameter(parameter)) {
+				if (isParameterDeclaredButNull(parameter, providedArgs)) {
+					args[i] = null;
+					continue;
+				}
 				throw new IllegalStateException(formatArgumentError(parameter, "No suitable resolver"));
 			}
 			try {
@@ -237,6 +241,27 @@ public void setMethodValidator(@Nullable MethodValidator methodValidator) {
 		return args;
 	}
 
+	/**
+	 * If there is null in providedArgs and the paramType does not have any non-null value matching, then consider null to be explicit.
+	 */
+	private boolean isParameterDeclaredButNull(MethodParameter parameter, @Nullable Object[] providedArgs) {
+		if (ObjectUtils.isEmpty(providedArgs)) {
+			return false;
+		}
+		Class<?> paramType = parameter.getParameterType();
+		boolean hasNull = false;
+		for (Object arg : providedArgs) {
+			if (arg == null) {
+				hasNull = true;
+				continue;
+			}
+			if (paramType.isAssignableFrom(arg.getClass())) {
+				return false;
+			}
+		}
+		return hasNull;
+	}
+
 	/**
 	 * Invoke the handler method with the given argument values.
 	 */