fix_average_duration_zero (#1164)

apm-collector/apm-collector-analysis/analysis-worker-model/src/main/java/org/apache/skywalking/apm/collector/analysis/worker/model/impl/AggregationWorker.java

@@ -82,6 +82,7 @@ public abstract class AggregationWorker<INPUT extends StreamData, OUTPUT extends
         if (mergeDataCache.containsKey(message.getId())) {
             mergeDataCache.get(message.getId()).mergeAndFormulaCalculateData(message);
         } else {
+            message.calculateFormula();
             mergeDataCache.put(message.getId(), message);
         }
         mergeDataCache.finishWriting();

apm-collector/apm-collector-core/src/main/java/org/apache/skywalking/apm/collector/core/data/AbstractData.java

@@ -156,7 +156,7 @@ public abstract class AbstractData {
     }
 
     @SuppressWarnings("unchecked")
-    private void calculateFormula() {
+    public void calculateFormula() {
         for (int i = 0; i < stringColumns.length; i++) {
             if (nonNull(stringColumns[i].getFormulaOperation())) {
                 String stringData = (String)stringColumns[i].getFormulaOperation().operate(this);