Add missing @Nullable annotations on parameters

Issue: SPR-15540

spring-web/src/test/java/org/springframework/http/converter/json/MappingJackson2HttpMessageConverterTests.java

@@ -39,6 +39,7 @@ import org.springframework.http.MockHttpInputMessage;
 import org.springframework.http.MockHttpOutputMessage;
 import org.springframework.http.converter.HttpMessageConversionException;
 import org.springframework.http.converter.HttpMessageNotReadableException;
+import org.springframework.lang.Nullable;
 
 import static org.hamcrest.CoreMatchers.containsString;
 import static org.hamcrest.CoreMatchers.endsWith;
@@ -169,7 +170,7 @@ public class MappingJackson2HttpMessageConverterTests {
 	public void readGenerics() throws IOException {
 		MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter() {
 			@Override
-			protected JavaType getJavaType(Type type, Class<?> contextClass) {
+			protected JavaType getJavaType(Type type, @Nullable Class<?> contextClass) {
 				if (type instanceof Class && List.class.isAssignableFrom((Class<?>)type)) {
 					return new ObjectMapper().getTypeFactory().constructCollectionType(ArrayList.class, MyBean.class);
 				}

spring-web/src/test/java/org/springframework/web/jsf/DelegatingNavigationHandlerTests.java

@@ -23,6 +23,7 @@ import org.junit.Test;
 
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.support.StaticListableBeanFactory;
+import org.springframework.lang.Nullable;
 
 import static org.junit.Assert.*;
 
@@ -91,7 +92,7 @@ public class DelegatingNavigationHandlerTests {
 
 		@Override
 		public void handleNavigation(
-				FacesContext facesContext, String fromAction, String outcome, NavigationHandler originalNavigationHandler) {
+				FacesContext facesContext, @Nullable String fromAction, @Nullable String outcome, @Nullable NavigationHandler originalNavigationHandler) {
 			lastFromAction = fromAction;
 			lastOutcome = outcome;
 			if (originalNavigationHandler != null) {