@Test
    public void testSetString() {
        Book book = new Book(new DocumentId("id:book:book::0"));
        book.setFieldValue("author", "Herman Melville");
        assertNotEquals(null, book.authorSpanTrees());
    }
Tests vespa-documentgen-plugin

@author vegardh
documentgen-test/src/test/java/com/yahoo/vespa/config/DocumentGenPluginTest.java