Map<String, Object> map = objectMapper.readValue(jsonString, new TypeReference<Map<String,Object>>(){});

JsonNode jsonNodeRoot = objectMapper.readTree(jsonString);
JsonNode jsonNodeYear = jsonNodeRoot.get("year");
String year = jsonNodeYear.asText();

import com.fasterxml.jackson.annotation.JsonInclude;
@JsonInclude(JsonInclude.Include.NON_NULL)