in spark-job/src/main/java/org/apache/cassandra/diff/Differ.java [304:314]
static Map<KeyspaceTablePair, RangeStats> accumulate(Map<KeyspaceTablePair, RangeStats> stats, Map<KeyspaceTablePair, RangeStats> otherStats)
{
for (Map.Entry<KeyspaceTablePair, RangeStats> otherEntry : otherStats.entrySet())
{
if (stats.containsKey(otherEntry.getKey()))
stats.get(otherEntry.getKey()).accumulate(otherEntry.getValue());
else
stats.put(otherEntry.getKey(), otherEntry.getValue());
}
return stats;
}