public Struct put(String fieldName, Object value) {
        Field field = lookupField(fieldName);
        return put(field, value);
    }
@Test
    public void testInvalidFieldType() {
        assertThrows(DataException.class,
            () -> new Struct(FLAT_STRUCT_SCHEMA).put("int8", "should fail because this is a string, not int8"));
    }