Jersey + Jackson can map to a String and a Map<String,Object>

jersey_jackson.java

import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

import javax.ws.rs.*;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

@Path("/some_path")
public class AnExampleResource {
  
    @POST
    @Path("/sub_path")
    @Consumes(MediaType.APPLICATION_JSON)
    @Produces(MediaType.APPLICATION_JSON)
    public String saveMethod( String inputJsonObj  ) throws IOException {
        
        // These steps seems to be SOP
        ObjectMapper mapper = new ObjectMapper();
        JsonFactory factory = mapper.getFactory();
        JsonParser jp = factory.createJsonParser( inputJsonObj );
        JsonNode actualObj = mapper.readTree( jp );
        
        // If you want a value
        String the_associated_value = actualObj.get( "a_key_in_the_input_json").textValue();
        return inputJsonObj;
    }
    
    @POST
    @Path("/sub_path2")
    @Consumes(MediaType.APPLICATION_JSON)
    @Produces(MediaType.APPLICATION_JSON)
    public Map<String,Object> saveMethod( Map<String,Object> params  ) throws IOException {
        
        // Processing steps
        
        return params;
    }
    
}