DATAMONGO-2370 - Polishing.

Align since version to 2.3 until we have an indication for a major version bump. Tweak docs.

Original pull request: #803.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/ArithmeticOperators.java

@@ -516,7 +516,7 @@ public class ArithmeticOperators {
 		 * place.
 		 *
 		 * @return new instance of {@link Round}.
-		 * @since 3.0
+		 * @since 2.3
 		 */
 		public Round round() {
 			return usesFieldRef() ? Round.roundValueOf(fieldReference) : Round.roundValueOf(expression);
@@ -526,7 +526,7 @@ public class ArithmeticOperators {
 		 * Creates new {@link AggregationExpression} that rounds a number to a specified decimal place.
 		 *
 		 * @return new instance of {@link Round}.
-		 * @since 3.0
+		 * @since 2.3
 		 */
 		public Round roundToPlace(int place) {
 			return round().place(place);
@@ -1445,7 +1445,7 @@ public class ArithmeticOperators {
 	}
 
 	/**
-	 * {@link Round} rounds a number to a whole integer or to a specified decimal place. <br />
+	 * {@link Round} rounds a number to a whole integer or to a specified decimal place.
 	 * <ul>
 	 * <li>If {@link Round#place(int)} resolves to a positive integer, {@code $round} rounds to the given decimal
 	 * places.</li>
@@ -1455,7 +1455,7 @@ public class ArithmeticOperators {
 	 * decimal.</li>
 	 * </ul>
 	 *
-	 * @since 3.0
+	 * @since 2.3
 	 */
 	public static class Round extends AbstractAggregationExpression {
 

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/ArithmeticOperatorsUnitTests.java

@@ -25,9 +25,10 @@ import org.bson.Document;
 import org.junit.jupiter.api.Test;
 
 /**
+ * Unit tests for {@link Round}.
+ *
  * @author Christoph Strobl
  */
-
 public class ArithmeticOperatorsUnitTests {
 
 	@Test // DATAMONGO-2370
@@ -41,7 +42,7 @@ public class ArithmeticOperatorsUnitTests {
 	void roundShouldWithPlace() {
 
 		assertThat(valueOf("field").roundToPlace(3).toDocument(Aggregation.DEFAULT_CONTEXT))
-				.isEqualTo(new Document("$round", Arrays.asList("$field", Integer.valueOf(3))));
+				.isEqualTo(new Document("$round", Arrays.asList("$field", 3)));
 	}
 
 	@Test // DATAMONGO-2370

src/main/asciidoc/reference/mongodb.adoc

@@ -2516,7 +2516,7 @@ At the time of this writing, we provide support for the following Aggregation Op
 | `addToSet`, `first`, `last`, `max`, `min`, `avg`, `push`, `sum`, `(*count)`, `stdDevPop`, `stdDevSamp`
 
 | Arithmetic Aggregation Operators
-| `abs`, `add` (*via `plus`), `ceil`, `divide`, `exp`, `floor`, `ln`, `log`, `log10`, `mod`, `multiply`, `pow`, `sqrt`, `subtract` (*via `minus`), `trunc`, `round`
+| `abs`, `add` (*via `plus`), `ceil`, `divide`, `exp`, `floor`, `ln`, `log`, `log10`, `mod`, `multiply`, `pow`, `round`, `sqrt`, `subtract` (*via `minus`), `trunc`
 
 | String Aggregation Operators
 | `concat`, `substr`, `toLower`, `toUpper`, `stcasecmp`, `indexOfBytes`, `indexOfCP`, `split`, `strLenBytes`, `strLenCP`, `substrCP`, `trim`, `ltrim`, `rtim`