Polishing.

Align type variable naming with imperative extensions(I, O). Add extension without accepting KClass. Update since tags and tests.

See #3508.
Original pull request: #893.

spring-data-mongodb/src/main/kotlin/org/springframework/data/mongodb/core/ReactiveMongoOperationsExtensions.kt

@@ -217,37 +217,46 @@ inline fun <reified T : Any, reified E : Any> ReactiveMongoOperations.findDistin
  * Extension for [ReactiveMongoOperations.aggregate] leveraging reified type parameters.
  *
  * @author Wonwoo Lee
- * @since 3.1
+ * @since 3.1.4
  */
-inline fun <reified T : Any> ReactiveMongoOperations.aggregate(aggregation: TypedAggregation<*>, collectionName: String): Flux<T> =
-		this.aggregate(aggregation, collectionName, T::class.java)
+inline fun <reified O : Any> ReactiveMongoOperations.aggregate(
+	aggregation: TypedAggregation<*>,
+	collectionName: String
+): Flux<O> =
+	this.aggregate(aggregation, collectionName, O::class.java)
 
 /**
  * Extension for [ReactiveMongoOperations.aggregate] leveraging reified type parameters.
  *
  * @author Wonwoo Lee
- * @since 3.1
+ * @since 3.1.4
  */
-inline fun <reified T : Any> ReactiveMongoOperations.aggregate(aggregation: TypedAggregation<*>): Flux<T> =
-		this.aggregate(aggregation, T::class.java)
+inline fun <reified O : Any> ReactiveMongoOperations.aggregate(aggregation: TypedAggregation<*>): Flux<O> =
+	this.aggregate(aggregation, O::class.java)
 
 /**
  * Extension for [ReactiveMongoOperations.aggregate] leveraging reified type parameters.
  *
  * @author Wonwoo Lee
- * @since 3.1
+ * @author Mark Paluch
+ * @since 3.1.4
  */
-inline fun <reified T : Any> ReactiveMongoOperations.aggregate(aggregation: Aggregation, entityClass: KClass<*>): Flux<T> =
-		this.aggregate(aggregation, entityClass.java, T::class.java)
+inline fun <reified I : Any, reified O : Any> ReactiveMongoOperations.aggregate(
+	aggregation: Aggregation
+): Flux<O> =
+	this.aggregate(aggregation, I::class.java, O::class.java)
 
 /**
  * Extension for [ReactiveMongoOperations.aggregate] leveraging reified type parameters.
  *
  * @author Wonwoo Lee
- * @since 3.1
+ * @since 3.1.4
  */
-inline fun <reified T : Any> ReactiveMongoOperations.aggregate(aggregation: Aggregation, collectionName: String): Flux<T> =
-		this.aggregate(aggregation, collectionName, T::class.java)
+inline fun <reified O : Any> ReactiveMongoOperations.aggregate(
+	aggregation: Aggregation,
+	collectionName: String
+): Flux<O> =
+	this.aggregate(aggregation, collectionName, O::class.java)
 
 /**
  * Extension for [ReactiveMongoOperations.geoNear] leveraging reified type parameters.

spring-data-mongodb/src/test/kotlin/org/springframework/data/mongodb/core/ReactiveMongoOperationsExtensionsTests.kt

@@ -30,6 +30,7 @@ import reactor.core.publisher.Mono
  * @author Sebastien Deleuze
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author Wonwoo Lee
  */
 class ReactiveMongoOperationsExtensionsTests {
 
@@ -607,10 +608,17 @@ class ReactiveMongoOperationsExtensionsTests {
 		val query = mockk<Query>()
 
 		operations.findDistinct<String>(query, "field", First::class)
-		verify { operations.findDistinct(query, "field", First::class.java, String::class.java) }
+		verify {
+			operations.findDistinct(
+				query,
+				"field",
+				First::class.java,
+				String::class.java
+			)
+		}
 	}
 
-	@Test
+	@Test  // #893
 	fun `aggregate(TypedAggregation, String, KClass) should call java counterpart`() {
 
 		val aggregation = mockk<TypedAggregation<String>>()
@@ -619,7 +627,7 @@ class ReactiveMongoOperationsExtensionsTests {
 		verify { operations.aggregate(aggregation, "foo", First::class.java) }
 	}
 
-	@Test
+	@Test // #893
 	fun `aggregate(TypedAggregation, KClass) should call java counterpart`() {
 
 		val aggregation = mockk<TypedAggregation<String>>()
@@ -628,16 +636,22 @@ class ReactiveMongoOperationsExtensionsTests {
 		verify { operations.aggregate(aggregation, First::class.java) }
 	}
 
-	@Test
+	@Test // #893
 	fun `aggregate(Aggregation, KClass) should call java counterpart`() {
 
 		val aggregation = mockk<Aggregation>()
 
-		operations.aggregate<First>(aggregation, String::class)
-		verify { operations.aggregate(aggregation, String::class.java, First::class.java) }
+		operations.aggregate<String, First>(aggregation)
+		verify {
+			operations.aggregate(
+				aggregation,
+				String::class.java,
+				First::class.java
+			)
+		}
 	}
 
-	@Test
+	@Test // #893
 	fun `aggregate(Aggregation, String) should call java counterpart`() {
 
 		val aggregation = mockk<Aggregation>()