public void merge(Coverage other) {
        if (other == null) return;

        docs += other.getDocs();
        nodes += other.getNodes();
        nodesTried += other.nodesTried;
        active += other.getActive();
        targetActive += other.getTargetActive();
        degradedReason |= other.degradedReason;
        resultSets += other.getResultSets();
        fullResultSets += other.getFullResultSets();

        // explicitly incomplete beats doc count beats explicitly full
        switch (other.fullReason) {
            case EXPLICITLY_FULL:
                // do nothing
                break;
            case EXPLICITLY_INCOMPLETE:
                fullReason = FullCoverageDefinition.EXPLICITLY_INCOMPLETE;
                break;
            case DOCUMENT_COUNT:
                if (fullReason == FullCoverageDefinition.EXPLICITLY_FULL) {
                    fullReason = FullCoverageDefinition.DOCUMENT_COUNT;
                }
                break;
        }
    }
The coverage report for a result set.

@author Steinar Knutsen
@author baldersheim
container-core/src/main/java/com/yahoo/container/handler/Coverage.java