childone.java

@Document
@JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, 
property = "@class")
public class ChildOne extends Parent {
	
	private long up;

	private long down;
}

childtwo.java

@Document
@JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, 
property = "@class")
public class ChildTwo extends ChildOne {
	
	private long timespan;
}

parent.java

@JsonTypeInfo(use=JsonTypeInfo.Id.CLASS, include=JsonTypeInfo.As.PROPERTY, property="@class")
@JsonSubTypes({
    @JsonSubTypes.Type(value = ChildOne.class),
    @JsonSubTypes.Type(value = ChildTwo	.class)
})
public class Parent extends AbstractDocument {
	
	private String blu;
	
}