Fixed tests

Author: kr-igor

dd-trace-core/src/main/java/datadog/trace/core/datastreams/DefaultDataStreamsMonitoring.java

@@ -409,8 +409,10 @@ private void flush(long timestampNanos) {
 
     if (!includedBuckets.isEmpty()) {
       for (Map.Entry<String, List<StatsBucket>> entry : includedBuckets.entrySet()) {
-        log.debug("Flushing {} buckets", entry.getValue());
-        payloadWriter.writePayload(entry.getValue(), entry.getKey());
+        if (!entry.getValue().isEmpty()) {
+          log.debug("Flushing {} buckets", entry.getValue());
+          payloadWriter.writePayload(entry.getValue(), entry.getKey());
+        }
       }
     }
   }

dd-trace-core/src/test/groovy/datadog/trace/core/datastreams/DataStreamsWritingTest.groovy

@@ -148,12 +148,10 @@ class DataStreamsWritingTest extends DDCoreSpecification {
 
     then:
     conditions.eventually {
-      assert requestBodies.size() > 0
+      assert requestBodies.size() == 1
     }
 
-    for (int i = 0; i < requestBodies.size(); i++) {
-      validateMessage(requestBodies[i])
-    }
+    validateMessage(requestBodies[0])
   }
 
   def validateMessage(byte[] message) {