@RequestMapping(value="/getContact", method=RequestMethod.GET,produces=MediaType.APPLICATION_JSON_VALUE)
public Contact getContact ()  {

    Contact s1 = new Contact();
    s1.setContactName("Avijit");
    s1.setContactType("Primary");
    return s1;
}

public class Contact {

private String contactName;
private String contactType;

public String getContactName() {
    return contactName;
}
public void setContactName(String contactNm) {
    this.contactName = contactNm;
}
public String getContactType() {
    return contactType;
}
public void setContactType(String contactType) {
    this.contactType = contactType;
}

{
    "contactName": "Avijit",
    "contactType": "Primary"
}

public class Contact {
    @JsonProperty(value="contactName")
    private String contactName;
    private String contactType;

    public String getContactName() {
        return contactName;
    }
    public void setContactName(String contactNm) {
        this.contactName = contactNm;
    }
    public String getContactType() {
        return contactType;
    }
    public void setContactType(String contactType) {
        this.contactType = contactType;
    }

}

{
    "contactType": "Primary",
    "contactName": "Avijit"
}