Deep merge for `JsonNode` using `ObjectReader.readTree()`

Is your feature request related to a problem? Please describe.

Describe the solution you’d like Ability to deep merge two JsonNode objects, and/or to deserialize a stream by updating an existing JsonNode rather than creating a new one.

Usage example

    var mapper = new ObjectMapper();
    var node1 = mapper.readTree("{\"root\":{\"a\":\"aaa\",\"foo\":\"hello\"}}");
    var node2 = mapper.readerForUpdating(node1)
        .readTree("{\"root\":{\"b\":\"bbb\",\"foo\":\"goodbye\"}}");

Additional context https://github.com/FasterXML/jackson-databind/issues/584 implies that this capability exists, but it does not appear to be functioning propery for JsonNode. There also doesn’t seem to be a way to specify shallow or deep merge using the tree API readerForUpdating()

[sirianni]

Thanks @cowtowncoder for the quick reply! I’ve created a repo https://github.com/sirianni/jsonMerge with a failing unit test.

[ollijm]

Ah I had a silly mistake, got it now:

        ObjectMapper mapper = new ObjectMapper();
        JsonNode node1 = mapper.readValue("{\"root\":{\"a\":\"aaa\",\"foo\":\"hello\"}}", JsonNode.class);
        JsonNode node2 = mapper.readerForUpdating(node1)
                .readValue("{\"root\":{\"b\":\"bbb\",\"foo\":\"goodbye\"}}");