public List<ValueUpdate> getValueUpdates(ValueUpdate.ValueUpdateClassID classID) {
        List<ValueUpdate> updateList = new ArrayList<>();
        for (ValueUpdate vupd : valueUpdates) {
            if (vupd.getValueUpdateClassID() == classID) {
                updateList.add(vupd);
            }
        }
        return updateList;
    }
Get value updates with the specified valueUpdateClassID. The caller gets ownership of the returned list, and
subsequent modifications to the list does not change the state of this object.

@param classID the classID of ValueUpdates to return
@return a List of ValueUpdates of the specified classID (possibly empty, but not null)
document/src/main/java/com/yahoo/document/update/FieldUpdate.java