String to Jackson JsonNode conversion in javacallout jar

[#1]

I'm getting the incoming array and json object into my java class using messageContext

but when I try to convert it into Jackson jsonNode using ObjectMapper's mapper.readTree(stringObj);

or using ObjectMapper's mapper.convertValue(schema, JsonNode.class) method then it is not working and neither it is giving error?

when I hit the api from post man it shows sending ..... and doesn't gives any result

Please help