protected void propagateNullOnNestedColumn(Function<Query, ResultIterable<? extends TestBean>> mapFunction) {

        try (Query select = handle.select("select 'fourty-two' as bean_id")) {
            // use the snake case column name mapper
            TestBean testBean = mapFunction.apply(select).one();

            assertThat(testBean).isNotNull();
            assertThat(testBean.getNestedBean()).isNotNull();
            assertThat(testBean.getNestedBean().getId()).isEqualTo("fourty-two");

            testBean = mapFunction.apply(handle.select("select NULL as bean_id")).one();

            assertThat(testBean).isNotNull()
                .extracting(TestBean::getNestedBean).isNull();
        }
    }
Test that the propagateNull annotation on a a specific column in the nested bean works. The annotation is picked up from the column (not from the bean).
core/src/test/java/org/jdbi/v3/core/mapper/AbstractPropagateNullTest.java