Update object-mapper/src/main/java/me/prettyprint/hom/HectorObjectMapper.java

addToExtraIfCan can be overwritten in order to modify mapping results. 
This can be used to return modification timestamp additionally to column value. 

Overwritten addToExtraIfCan-method could look like:
@Override protected <T> void addToExtraIfCan(....){
        if (null == meth) {throw new....}
        if (cfMapDef.getAnonymousValueType() == ColumnValue.class) {
            T value = (T) cfMapDef.getAnonymousValueSerializer().fromBytes(col.getValue());
            ColumnValue<T> val = new ColumnValue<T>(value, col.getClock());
            meth.invoke(obj, col.getName(), val);
        } else {
            meth.invoke(obj, col.getName(), cfMapDef.getAnonymousValueSerializer().fromBytes(col.getValue()));
        }
}

public final class ColumnValue<T> {
    public final Object value;
    public final long timestamp;
    public ColumnValue(Object value, long timestamp) {
        this.value = value;
        this.timestamp = timestamp;
    }
}