### Question:
JsonNodeBuilder { public boolean includeNulls() { return includeNulls; }  boolean includeNulls(); void includeNulls(boolean include); JsonNodeBuilder add(String key, JsonNode value); JsonNodeBuilder add(String key, java.util.Comparator value); JsonNodeBuilder add(String key, Long value); JsonNodeBuilder add(String key, Boolean value); JsonNodeBuilder add(String key, OperationStatus value); JsonNodeBuilder add(String key, JsonObject value); JsonNodeBuilder add(String key, List<T> values); JsonNodeBuilder addJsonObjectsList(String key, List<? extends JsonObject> values); JsonNodeBuilder addErrorsList(String key, List<Error> values); JsonNodeBuilder add(String key, String value); JsonNode build();  }### Answer:
@Test public void testIncludeNullsDefault() { assertFalse(builder.includeNulls()); }
@Test public void testIncludeNullsTrue() { builder.includeNulls(true); assertTrue(builder.includeNulls()); }