Polishing.

Ignore warnings for already checked constructs null away does not understand.

Original Pull Request: #3282

src/main/java/org/springframework/data/mapping/Parameter.java

@@ -118,6 +118,7 @@ public class Parameter<T, P extends PersistentProperty<P>> {
 	 * @since 3.5
 	 * @see org.springframework.core.ParameterNameDiscoverer
 	 */
+	@SuppressWarnings("NullAway")
 	public String getRequiredName() {
 
 		if (!hasName()) {

src/main/java/org/springframework/data/repository/query/Parameter.java

@@ -125,6 +125,7 @@ public class Parameter {
 	 *
 	 * @return
 	 */
+	@SuppressWarnings("NullAway")
 	public String getPlaceholder() {
 
 		if (isNamedParameter()) {