hollow/src/main/java/com/netflix/hollow/api/producer/validation/RecordCountVarianceValidator.java
float getChangePercent(int latestCardinality, int previousCardinality) {
        int diff = Math.abs(latestCardinality - previousCardinality);
        return (100.0f * diff) / previousCardinality;
    }
float getChangePercent(int latestCardinality, int previousCardinality) {
        int diff = Math.abs(latestCardinality - previousCardinality);
        return (100.0f * diff) / previousCardinality;
    }
protected for tests