DATACMNS-1141 - Add missing NonNullApi and Nullable annotations.

Add Nullable annotation to ParsingUtils, Sort.Order and PropertyValueProvider.

Add getRequiredAnnotation(…) to PersistentEntity and PersistentProperty to provide methods returning required, non-null annotations.

src/main/java/org/springframework/data/domain/Sort.java

@@ -414,7 +414,7 @@ public class Sort implements Streamable<org.springframework.data.domain.Sort.Ord
 		 * @param direction can be {@literal null}, will default to {@link Sort#DEFAULT_DIRECTION}
 		 * @param property must not be {@literal null} or empty.
 		 */
-		public Order(Direction direction, String property) {
+		public Order(@Nullable Direction direction, String property) {
 			this(direction, property, DEFAULT_IGNORE_CASE, DEFAULT_NULL_HANDLING);
 		}
 
@@ -426,7 +426,7 @@ public class Sort implements Streamable<org.springframework.data.domain.Sort.Ord
 		 * @param property must not be {@literal null} or empty.
 		 * @param nullHandling must not be {@literal null}.
 		 */
-		public Order(Direction direction, String property, NullHandling nullHandlingHint) {
+		public Order(@Nullable Direction direction, String property, NullHandling nullHandlingHint) {
 			this(direction, property, DEFAULT_IGNORE_CASE, nullHandlingHint);
 		}
 
@@ -485,7 +485,7 @@ public class Sort implements Streamable<org.springframework.data.domain.Sort.Ord
 		 * @param nullHandling must not be {@literal null}.
 		 * @since 1.7
 		 */
-		private Order(Direction direction, String property, boolean ignoreCase, NullHandling nullHandling) {
+		private Order(@Nullable Direction direction, String property, boolean ignoreCase, NullHandling nullHandling) {
 
 			if (!StringUtils.hasText(property)) {
 				throw new IllegalArgumentException("Property must not null or empty!");