protected boolean isSimpleTypeNode(JsonNode jsonNode) {
        if (!jsonNode.isObject()) {
            return false;
        }
        ObjectNode objectNode = (ObjectNode) jsonNode;
        int numberOfFields = objectNode.size();
        return numberOfFields == 1 && objectNode.has(VALUE);
    }
@Test
    public void isSimpleTypeNode_emptyNode() {
        assertThat(expressionEvaluator.isSimpleTypeNode(new ArrayNode(factory))).isFalse();
    }