Refine Kotlin extensions for MongoOperations.aggregate and aggregateStream

We now provide extensions accepting the input- and output type as reified generic types.

See #3508.

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

@@ -220,9 +220,24 @@ inline fun <reified T : Any> MongoOperations.group(criteria: Criteria, inputColl
  * @author Sebastien Deleuze
  * @since 2.0
  */
-@Deprecated("Since 2.2, use the reified variant", replaceWith = ReplaceWith("aggregate<T>(aggregation)"))
-inline fun <reified O : Any> MongoOperations.aggregate(aggregation: Aggregation, inputType: KClass<*>): AggregationResults<O> =
-		aggregate(aggregation, inputType.java, O::class.java)
+@Deprecated(
+	"Since 2.2, use the reified variant",
+	replaceWith = ReplaceWith("aggregate<I, O>(aggregation)")
+)
+inline fun <reified O : Any> MongoOperations.aggregate(
+	aggregation: Aggregation,
+	inputType: KClass<*>
+): AggregationResults<O> =
+	aggregate(aggregation, inputType.java, O::class.java)
+
+/**
+ * Extension for [MongoOperations.aggregate] leveraging reified type parameters.
+ *
+ * @author Mark Paluch
+ * @since 3.2
+ */
+inline fun <reified I : Any, reified O : Any> MongoOperations.aggregate(aggregation: Aggregation): AggregationResults<O> =
+	aggregate(aggregation, I::class.java, O::class.java)
 
 /**
  * Extension for [MongoOperations.aggregate] leveraging reified type parameters.
@@ -230,8 +245,11 @@ inline fun <reified O : Any> MongoOperations.aggregate(aggregation: Aggregation,
  * @author Sebastien Deleuze
  * @since 2.0
  */
-inline fun <reified O : Any> MongoOperations.aggregate(aggregation: Aggregation, collectionName: String): AggregationResults<O> =
-		aggregate(aggregation, collectionName, O::class.java)
+inline fun <reified O : Any> MongoOperations.aggregate(
+	aggregation: Aggregation,
+	collectionName: String
+): AggregationResults<O> =
+	aggregate(aggregation, collectionName, O::class.java)
 
 /**
  * Extension for [MongoOperations.aggregateStream] leveraging reified type parameters.
@@ -239,9 +257,24 @@ inline fun <reified O : Any> MongoOperations.aggregate(aggregation: Aggregation,
  * @author Sebastien Deleuze
  * @since 2.0
  */
-@Deprecated("Since 2.2, use the reified variant", replaceWith = ReplaceWith("aggregateStream<T>(aggregation)"))
-inline fun <reified O : Any> MongoOperations.aggregateStream(aggregation: Aggregation, inputType: KClass<*>): CloseableIterator<O> =
-		aggregateStream(aggregation, inputType.java, O::class.java)
+@Deprecated(
+	"Since 2.2, use the reified variant",
+	replaceWith = ReplaceWith("aggregateStream<I, O>(aggregation)")
+)
+inline fun <reified O : Any> MongoOperations.aggregateStream(
+	aggregation: Aggregation,
+	inputType: KClass<*>
+): CloseableIterator<O> =
+	aggregateStream(aggregation, inputType.java, O::class.java)
+
+/**
+ * Extension for [MongoOperations.aggregateStream] leveraging reified type parameters.
+ *
+ * @author Mark Paluch
+ * @since 3.2
+ */
+inline fun <reified I : Any, reified O : Any> MongoOperations.aggregateStream(aggregation: Aggregation): CloseableIterator<O> =
+	aggregateStream(aggregation, I::class.java, O::class.java)
 
 /**
  * Extension for [MongoOperations.aggregateStream] leveraging reified type parameters.
@@ -249,8 +282,11 @@ inline fun <reified O : Any> MongoOperations.aggregateStream(aggregation: Aggreg
  * @author Sebastien Deleuze
  * @since 2.0
  */
-inline fun <reified O : Any> MongoOperations.aggregateStream(aggregation: Aggregation, collectionName: String): CloseableIterator<O> =
-		aggregateStream(aggregation, collectionName, O::class.java)
+inline fun <reified O : Any> MongoOperations.aggregateStream(
+	aggregation: Aggregation,
+	collectionName: String
+): CloseableIterator<O> =
+	aggregateStream(aggregation, collectionName, O::class.java)
 
 /**
  * Extension for [MongoOperations.mapReduce] leveraging reified type parameters.

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

@@ -241,7 +241,28 @@ class MongoOperationsExtensionsTests {
 		val aggregation = mockk<Aggregation>()
 
 		operations.aggregate<First>(aggregation, Second::class)
-		verify { operations.aggregate(aggregation, Second::class.java, First::class.java) }
+		verify {
+			operations.aggregate(
+				aggregation,
+				Second::class.java,
+				First::class.java
+			)
+		}
+	}
+
+	@Test // #3508
+	fun `aggregate(Aggregation) with reified type parameter extension should call its Java counterpart`() {
+
+		val aggregation = mockk<Aggregation>()
+
+		operations.aggregate<Second, First>(aggregation)
+		verify {
+			operations.aggregate(
+				aggregation,
+				Second::class.java,
+				First::class.java
+			)
+		}
 	}
 
 	@Test // DATAMONGO-1689
@@ -261,7 +282,28 @@ class MongoOperationsExtensionsTests {
 		val aggregation = mockk<Aggregation>()
 
 		operations.aggregateStream<First>(aggregation, Second::class)
-		verify { operations.aggregateStream(aggregation, Second::class.java, First::class.java) }
+		verify {
+			operations.aggregateStream(
+				aggregation,
+				Second::class.java,
+				First::class.java
+			)
+		}
+	}
+
+	@Test // #3508
+	fun `aggregateStream(Aggregation) with reified type parameter extension should call its Java counterpart`() {
+
+		val aggregation = mockk<Aggregation>()
+
+		operations.aggregateStream<Second, First>(aggregation)
+		verify {
+			operations.aggregateStream(
+				aggregation,
+				Second::class.java,
+				First::class.java
+			)
+		}
 	}
 
 	@Test // DATAMONGO-1689
@@ -271,7 +313,13 @@ class MongoOperationsExtensionsTests {
 		val collectionName = "foo"
 
 		operations.aggregateStream<First>(aggregation, collectionName)
-		verify { operations.aggregateStream(aggregation, collectionName, First::class.java) }
+		verify {
+			operations.aggregateStream(
+				aggregation,
+				collectionName,
+				First::class.java
+			)
+		}
 	}
 
 	@Test // DATAMONGO-1689