Specify generic type nullness in spring-r2dbc

See gh-34140

spring-r2dbc/src/main/java/org/springframework/r2dbc/core/BeanPropertyRowMapper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -125,7 +125,7 @@ public class BeanPropertyRowMapper<T> implements Function<Readable, T> {
 	 * Remove the specified property from the mapped properties.
 	 * @param propertyName the property name (as used by property descriptors)
 	 */
-	protected void suppressProperty(String propertyName) {
+	protected void suppressProperty(@Nullable String propertyName) {
 		this.mappedProperties.remove(lowerCaseName(propertyName));
 		this.mappedProperties.remove(underscoreName(propertyName));
 	}
@@ -136,7 +136,10 @@ public class BeanPropertyRowMapper<T> implements Function<Readable, T> {
 	 * @param name the original name
 	 * @return the converted name
 	 */
-	protected String lowerCaseName(String name) {
+	protected String lowerCaseName(@Nullable String name) {
+		if (!StringUtils.hasLength(name)) {
+			return "";
+		}
 		return name.toLowerCase(Locale.US);
 	}
 
@@ -147,7 +150,7 @@ public class BeanPropertyRowMapper<T> implements Function<Readable, T> {
 	 * @return the converted name
 	 * @see #lowerCaseName
 	 */
-	protected String underscoreName(String name) {
+	protected String underscoreName(@Nullable String name) {
 		if (!StringUtils.hasLength(name)) {
 			return "";
 		}

spring-r2dbc/src/main/java/org/springframework/r2dbc/core/DataClassRowMapper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -21,6 +21,7 @@ import java.util.List;
 
 import io.r2dbc.spi.Readable;
 import io.r2dbc.spi.ReadableMetadata;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.BeanUtils;
 import org.springframework.beans.TypeConverter;
@@ -66,7 +67,7 @@ public class DataClassRowMapper<T> extends BeanPropertyRowMapper<T> {
 
 	private final Constructor<T> mappedConstructor;
 
-	private final String[] constructorParameterNames;
+	private final @Nullable String[] constructorParameterNames;
 
 	private final TypeDescriptor[] constructorParameterTypes;
 
@@ -98,7 +99,7 @@ public class DataClassRowMapper<T> extends BeanPropertyRowMapper<T> {
 
 	@Override
 	protected T constructMappedInstance(Readable readable, List<? extends ReadableMetadata> itemMetadatas, TypeConverter tc) {
-		Object[] args = new Object[this.constructorParameterNames.length];
+		@Nullable Object[] args = new Object[this.constructorParameterNames.length];
 		for (int i = 0; i < args.length; i++) {
 			String name = this.constructorParameterNames[i];
 			int index = findIndex(itemMetadatas, lowerCaseName(name));