JAVA-5971 Reverse equals check to avoid NPEs (#1806)

Fixes NPE due to BSONIgnore fields introduced in #1610

JAVA-5971

---------

Co-authored-by: Ross Lawley <[email protected]>

Author: owen-obrien

bson/src/main/org/bson/codecs/pojo/ConventionAnnotationImpl.java

@@ -34,6 +34,7 @@
 import java.lang.reflect.Type;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Objects;
 import java.util.Map;
 
 import static java.lang.String.format;
@@ -244,7 +245,7 @@ private void cleanPropertyBuilders(final ClassModelBuilder<?> classModelBuilder)
             if (!propertyModelBuilder.isReadable() && !propertyModelBuilder.isWritable()) {
                 propertiesToRemove.add(propertyModelBuilder.getName());
             }
-            if (classModelBuilder.useDiscriminator() && propertyModelBuilder.getReadName().equals(classModelBuilder.getDiscriminatorKey())) {
+            if (classModelBuilder.useDiscriminator() && Objects.equals(classModelBuilder.getDiscriminatorKey(), propertyModelBuilder.getReadName())) {
                 propertiesToRemove.add(propertyModelBuilder.getName());
                 LOGGER.warn(
                         format(

bson/src/test/unit/org/bson/codecs/pojo/PojoCodecDiscriminatorTest.java

@@ -19,6 +19,7 @@
 import org.bson.codecs.pojo.entities.DiscriminatorModel;
 import org.bson.codecs.pojo.entities.DiscriminatorWithGetterModel;
 import org.bson.codecs.pojo.entities.DiscriminatorWithProperty;
+import org.bson.codecs.pojo.entities.DiscriminatorWithPropertyAndIgnore;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertArrayEquals;
@@ -70,4 +71,12 @@ public void testDiscriminatorRoundTripWhenItIsAlsoAProperty() {
                 "{discriminatorKey:'discriminatorValue'}"
         );
     }
+
+    @Test
+    public void testDiscriminatorRoundTripWhenItIsAlsoAPropertyWithIgnoredProperty() {
+        roundTrip(
+                new DiscriminatorWithPropertyAndIgnore(),
+                "{discriminatorKey:'discriminatorValue'}"
+        );
+    }
 }

bson/src/test/unit/org/bson/codecs/pojo/entities/DiscriminatorWithPropertyAndIgnore.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2008-present MongoDB, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.bson.codecs.pojo.entities;
+
+import org.bson.codecs.pojo.annotations.BsonDiscriminator;
+import org.bson.codecs.pojo.annotations.BsonIgnore;
+import org.bson.codecs.pojo.annotations.BsonProperty;
+
+import java.util.Objects;
+
+@BsonDiscriminator(key = "discriminatorKey", value = "discriminatorValue")
+public class DiscriminatorWithPropertyAndIgnore {
+
+    public DiscriminatorWithPropertyAndIgnore() {
+    }
+
+    @BsonIgnore
+    public String getFoo() {
+        return "foo";
+    }
+
+    @BsonProperty("discriminatorKey")
+    public String getDiscriminator() {
+        return "discriminatorValue";
+    }
+
+    @Override
+    public boolean equals(final Object o) {
+        if (o == null || getClass() != o.getClass()){
+            return false;
+        }
+        final DiscriminatorWithPropertyAndIgnore that = (DiscriminatorWithPropertyAndIgnore) o;
+        return Objects.equals(getDiscriminator(), that.getDiscriminator());
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hashCode(getDiscriminator());
+    }
+
+    @Override
+    public String toString() {
+        return "DiscriminatorWithProperty{}";
+    }
+}