Fix field inclusion in aggregation project operation.

Closes #3898
Original pull request: #3904.

Author: christophstrobl

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

@@ -1803,8 +1803,9 @@ public Document toDocument(AggregationOperationContext context) {
 			Document projections = new Document();
 
 			Fields fields = context.getFields(type);
-			fields.forEach(it -> projections.append(it.getName(), 1));
-			return context.getMappedObject(projections, type);
+
+			fields.forEach(it -> projections.append(it.getTarget(), 1));
+			return projections;
 		}
 	}
 

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

@@ -122,13 +122,13 @@ public Fields getFields(Class<?> type) {
 			return AggregationOperationContext.super.getFields(type);
 		}
 
-		List<String> fields = new ArrayList<>();
+		List<Field> fields = new ArrayList<>();
 
 		for (MongoPersistentProperty property : entity) {
-			fields.add(property.getName());
+			fields.add(Fields.field(property.getName(), property.getFieldName()));
 		}
 
-		return Fields.fields(fields.toArray(new String[0]));
+		return Fields.from(fields.toArray(new Field[0]));
 	}
 
 	/*

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

@@ -27,6 +27,7 @@
 
 import org.bson.Document;
 import org.junit.jupiter.api.Test;
+import org.springframework.data.annotation.Id;
 import org.springframework.data.domain.Sort.Direction;
 import org.springframework.data.mongodb.core.aggregation.ConditionalOperators.Cond;
 import org.springframework.data.mongodb.core.aggregation.ProjectionOperationUnitTests.BookWithFieldAnnotation;
@@ -598,9 +599,31 @@ void projectOnIdIsAlwaysValid() {
 		assertThat(extractPipelineElement(target, 1, "$project")).isEqualTo(Document.parse(" { \"_id\" : \"$_id\" }"));
 	}
 
+
+	@Test // GH-3898
+	void shouldNotConvertIncludeExcludeValuesForProjectOperation() {
+
+		MongoMappingContext mappingContext = new MongoMappingContext();
+		RelaxedTypeBasedAggregationOperationContext context = new RelaxedTypeBasedAggregationOperationContext(WithRetypedIdField.class, mappingContext,
+				new QueryMapper(new MappingMongoConverter(NoOpDbRefResolver.INSTANCE, mappingContext)));
+		Document document = project(WithRetypedIdField.class).toDocument(context);
+		assertThat(document).isEqualTo(new Document("$project", new Document("_id", 1).append("renamed-field", 1)));
+	}
+
 	private Document extractPipelineElement(Document agg, int index, String operation) {
 
 		List<Document> pipeline = (List<Document>) agg.get("pipeline");
 		return (Document) pipeline.get(index).get(operation);
 	}
+
+	public class WithRetypedIdField {
+
+		@Id
+		@org.springframework.data.mongodb.core.mapping.Field
+		private String id;
+
+		@org.springframework.data.mongodb.core.mapping.Field("renamed-field")
+		private String foo;
+
+	}
 }