Consistently declare Object::equals argument as @Nullable

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

@@ -398,7 +398,7 @@ abstract class NamedParameterUtils {
 		}
 
 		@Override
-		public boolean equals(Object o) {
+		public boolean equals(@Nullable Object o) {
 			if (this == o) {
 				return true;
 			}

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

@@ -111,7 +111,7 @@ public final class Parameter {
 
 
 	@Override
-	public boolean equals(Object obj) {
+	public boolean equals(@Nullable Object obj) {
 		if (this == obj) {
 			return true;
 		}