The convertValue function is used to convert one instance type into another instance type. It is a two step conversion process which is equivalent to first serializing given value into JSON, then binding JSON data into value of second given type.

In your example above, the first argument of convertValue is actually a JSON(represented in a string) and not an object, hence this does not work.

To make this work, you can use following methods :

Method 1 :

JsonNode node = jsonMapper.readTree(jsonRoot);

This will deserialize the json as a tree and returns the root of the tree which can be used for traversal now.

Method 2 :

JsonNode node = jsonMapper.readValue(jsonRoot, JsonNode.class);

This will deserialize the json to JsonNode object directly.

Here is the solution by "Josson & Jossons". I list 2 more examples with condition filtering.

https://github.com/octomix/josson

implementation 'com.octomix.josson:josson:1.3.22'

---------------------------------------------

Josson josson = Josson.fromJsonString(
    "[" +
    "  {" +
    "    \"item\": {" +
    "      \"type\": \"uri\", \"value\": \"http://www.wikidata.org/entity/Q42442324\"" +
    "    }," +
    "    \"prop\": {" +
    "      \"type\": \"uri\", \"value\": \"http://www.wikidata.org/prop/direct/P21\"" +
    "    }," +
    "    \"itemLabel\": {" +
    "      \"xml:lang\": \"en\", \"type\": \"literal\", \"value\": \"Kiisu Miisu\"" +
    "    }" +
    "  }," +
    "  {" +
    "    \"item\": {" +
    "      \"type\": \"uri\", \"value\": \"http://www.wikidata.org/entity/Q43260736\"" +
    "    }," +
    "    \"prop\": {" +
    "      \"type\": \"uri\", \"value\": \"http://www.wikidata.org/prop/direct/P21\"" +
    "    }," +
    "    \"itemLabel\": {" +
    "      \"xml:lang\": \"en\", \"type\": \"literal\", \"value\": \"Paddles\"" +
    "    }" +
    "  }" +
    "]");

JsonNode node = josson.getNode("*.value");
System.out.println("1.\n" + node.toPrettyString());

node = josson.getNode("~'^item.*'.value");
System.out.println("2.\n" + node.toPrettyString());

node = josson.getNode("*[value.type='uri']*.value");
System.out.println("3.\n" + node.toPrettyString());

Output:

1.
[ "http://www.wikidata.org/entity/Q42442324", "http://www.wikidata.org/prop/direct/P21", "Kiisu Miisu", "http://www.wikidata.org/entity/Q43260736", "http://www.wikidata.org/prop/direct/P21", "Paddles" ]
2.
[ "http://www.wikidata.org/entity/Q42442324", "Kiisu Miisu", "http://www.wikidata.org/entity/Q43260736", "Paddles" ]
3.
[ "http://www.wikidata.org/entity/Q42442324", "http://www.wikidata.org/prop/direct/P21", "http://www.wikidata.org/entity/Q43260736", "http://www.wikidata.org/prop/direct/P21" ]