ternary nullness logic implementation

src/integrationTest/java/com/mongodb/hibernate/query/select/Book.java

@@ -43,6 +43,20 @@ class Book {
         this.outOfStock = outOfStock;
     }
 
+    public Book(
+            int id,
+            String title,
+            Integer publishYear,
+            Boolean outOfStock,
+            Long isbn13,
+            Double discount,
+            BigDecimal price) {
+        this(id, title, publishYear, outOfStock);
+        this.isbn13 = isbn13;
+        this.discount = discount;
+        this.price = price;
+    }
+
     @Override
     public String toString() {
         return "Book{" + "id=" + id + '}';

src/integrationTest/java/com/mongodb/hibernate/query/select/BooleanExpressionWhereClauseIntegrationTests.java

@@ -54,9 +54,41 @@ void testBooleanFieldPathExpression(boolean negated) {
         assertSelectionQuery(
                 "from Book where" + (negated ? " not " : " ") + "outOfStock",
                 Book.class,
-                "{'aggregate': 'books', 'pipeline': [{'$match': {'outOfStock': {'$eq': "
-                        + (negated ? "false" : "true")
-                        + "}}}, {'$project': {'_id': true, 'discount': true, 'isbn13': true, 'outOfStock': true, 'price': true, 'publishYear': true, 'title': true}}]}",
+                """
+                {
+                  "aggregate": "books",
+                  "pipeline": [
+                    {
+                      "$match": {
+                        "$and": [
+                          {
+                            "outOfStock": {
+                              "$eq": %s
+                            }
+                          },
+                          {
+                            "outOfStock": {
+                              "$ne": null
+                            }
+                          }
+                        ]
+                      }
+                    },
+                    {
+                      "$project": {
+                        "_id": true,
+                        "discount": true,
+                        "isbn13": true,
+                        "outOfStock": true,
+                        "price": true,
+                        "publishYear": true,
+                        "title": true
+                      }
+                    }
+                  ]
+                }
+                """
+                        .formatted(negated ? "false" : "true"),
                 negated ? singletonList(bookInStock) : singletonList(bookOutOfStock));
     }