Fix NPE error with ConventionSetPrivateField

JAVA-2951

Author: rozza

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

@@ -33,7 +33,8 @@ public void apply(final ClassModelBuilder<?> classModelBuilder) {
             }
             PropertyAccessorImpl<?> defaultAccessor = (PropertyAccessorImpl<?>) propertyModelBuilder.getPropertyAccessor();
             PropertyMetadata<?> propertyMetaData = defaultAccessor.getPropertyMetadata();
-            if (!propertyMetaData.isDeserializable() && isPrivate(propertyMetaData.getField().getModifiers())) {
+            if (!propertyMetaData.isDeserializable() && propertyMetaData.getField() != null
+                    && isPrivate(propertyMetaData.getField().getModifiers())) {
                 setPropertyAccessor(propertyModelBuilder);
             }
         }

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

@@ -184,7 +184,7 @@ public void testSetPrivateFieldConvention() {
         builder.conventions(conventions);
 
         roundTrip(builder, new PrivateSetterFieldModel(1, "2", asList("a", "b")),
-                "{'integerField': 1, 'stringField': '2', listField: ['a', 'b']}");
+                "{'someMethod': 'some method', 'integerField': 1, 'stringField': '2', listField: ['a', 'b']}");
     }
 
     @Test

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

@@ -33,6 +33,10 @@ public PrivateSetterFieldModel(final Integer integerField, final String stringFi
         this.listField = listField;
     }
 
+    public String getSomeMethod() {
+        return "some method";
+    }
+
     public Integer getIntegerField() {
         return integerField;
     }