import java.util.HashMap;
import java.util.Map;

import com.fasterxml.jackson.annotation.JsonAnyGetter;
import com.fasterxml.jackson.annotation.JsonAnySetter;
import com.fasterxml.jackson.annotation.JsonInclude;

@JsonInclude(JsonInclude.Include.NON_NULL)
public class TestClass {
    private String context_id;
    private Map<String, String> properties = new HashMap<>();

    public String getContext_id() {
        return context_id;
    }
    public void setContext_id(String context_id) {
        this.context_id = context_id;
    }
    @JsonAnySetter
    public void set(String fieldName, String value){
        this.properties.put(fieldName, value);
    }
    @JsonAnyGetter
    public Map<String, String> any() {
        return this.properties;
    }
    public String get(String fieldName){
        return this.properties.get(fieldName);
    }
}

{
    "context_id": "14",
    "io": "odp"
}

{
            "context_id": "14",
            "properties" : {
                   "io": "odp"
             },
            "io": "odp"
}

{
        "context_id": "14",
        "properties" : {
               "io": "odp"
         }
}