Polishing.

Update java doc and add issue references to tests.

Original Pull Request: #3858

Author: christophstrobl

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

@@ -799,12 +799,12 @@ public Cosh cosh() {
 		public Cosh cosh(AngularUnit unit) {
 			return usesFieldRef() ? Cosh.coshOf(fieldReference, unit) : Cosh.coshOf(expression, unit);
 		}
-		
+
 		/**
 		 * Creates new {@link AggregationExpression} that calculates the inverse cosine of a numeric value.
 		 *
 		 * @return new instance of {@link ACos}.
-		 * @since 3.3
+		 * @since 3.4
 		 */
 		public ACos acos() {
 			return usesFieldRef() ? ACos.acosOf(fieldReference) : ACos.acosOf(expression);
@@ -814,7 +814,7 @@ public ACos acos() {
 		 * Creates new {@link AggregationExpression} that calculates the inverse hyperbolic cosine of a numeric value.
 		 *
 		 * @return new instance of {@link ACosh}.
-		 * @since 3.3
+		 * @since 3.4
 		 */
 		public ACosh acosh() {
 			return usesFieldRef() ? ACosh.acoshOf(fieldReference) : ACosh.acoshOf(expression);
@@ -2482,7 +2482,6 @@ protected String getMongoMethod() {
 		}
 	}
 
-
 	/**
 	 * An {@link AggregationExpression expression} that calculates the cosine of a value that is measured in radians.
 	 *
@@ -2684,10 +2683,12 @@ protected String getMongoMethod() {
 			return "$cosh";
 		}
 	}
-	
+
 	/**
 	 * An {@link AggregationExpression expression} that calculates the inverse cosine of a value.
 	 *
+	 * @author Divya Srivastava
+	 * @since 3.4
 	 */
 	public static class ACos extends AbstractAggregationExpression {
 
@@ -2736,8 +2737,10 @@ protected String getMongoMethod() {
 	}
 
 	/**
-	 * An {@link AggregationExpression expression} that calculates the inverse hyperbolic cosine of a value
+	 * An {@link AggregationExpression expression} that calculates the inverse hyperbolic cosine of a value.
 	 *
+	 * @author Divya Srivastava
+	 * @since 3.4
 	 */
 	public static class ACosh extends AbstractAggregationExpression {
 
@@ -2972,7 +2975,6 @@ public static ATan2 valueOf(AggregationExpression expression) {
 			return new ATan2((Collections.singletonList(expression)));
 		}
 
-
 		/**
 		 * Creates a new {@link AggregationExpression} that calculates the inverse tangent of of y / x, where y and x are
 		 * the first and second values passed to the expression respectively.

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

@@ -139,12 +139,12 @@ void rendersCosh() {
 		assertThat(valueOf("angle").cosh().toDocument(Aggregation.DEFAULT_CONTEXT)).isEqualTo("{ $cosh : \"$angle\" }");
 	}
 
-	@Test 
+	@Test // GH-3707
 	void rendersACos() {
 		assertThat(valueOf("field").acos().toDocument(Aggregation.DEFAULT_CONTEXT)).isEqualTo("{ $acos : \"$field\" }");
 	}
 
-	@Test 
+	@Test // GH-3707
 	void rendersACosh() {
 		assertThat(valueOf("field").acosh().toDocument(Aggregation.DEFAULT_CONTEXT)).isEqualTo("{ $acosh : \"$field\" }");
 	}

src/main/asciidoc/reference/aggregation-framework.adoc

@@ -85,7 +85,7 @@ At the time of this writing, we provide support for the following Aggregation Op
 | `addToSet`, `covariancePop`, `covarianceSamp`, `expMovingAvg`, `first`, `last`, `max`, `min`, `avg`, `push`, `sum`, `count` (+++*+++), `stdDevPop`, `stdDevSamp`
 
 | Arithmetic Aggregation Operators
-| `abs`, `add` (+++*+++ via `plus`), `asin`, `asin`, `atan`, `atan2`, `atanh`, `ceil`, `cos`, `cosh`, `derivative`, `divide`, `exp`, `floor`, `integral`, `ln`, `log`, `log10`, `mod`, `multiply`, `pow`, `round`, `sqrt`, `subtract` (+++*+++ via `minus`), `sin`, `sinh`, `tan`, `tanh`, `trunc`
+| `abs`, `acos`, `acosh`, `add` (+++*+++ via `plus`), `asin`, `asin`, `atan`, `atan2`, `atanh`, `ceil`, `cos`, `cosh`, `derivative`, `divide`, `exp`, `floor`, `integral`, `ln`, `log`, `log10`, `mod`, `multiply`, `pow`, `round`, `sqrt`, `subtract` (+++*+++ via `minus`), `sin`, `sinh`, `tan`, `tanh`, `trunc`
 
 | String Aggregation Operators
 | `concat`, `substr`, `toLower`, `toUpper`, `strcasecmp`, `indexOfBytes`, `indexOfCP`, `regexFind`, `regexFindAll`, `regexMatch`, `split`, `strLenBytes`, `strLenCP`, `substrCP`, `trim`, `ltrim`, `rtim`