Fix transaction id copy (#288)

Author: eyalkoren

apm-agent-core/src/main/java/co/elastic/apm/impl/transaction/TraceContext.java

@@ -344,6 +344,7 @@ public void copyFrom(TraceContext other) {
         traceId.copyFrom(other.traceId);
         id.copyFrom(other.id);
         parentId.copyFrom(other.parentId);
+        transactionId.copyFrom(other.transactionId);
         outgoingHeader.append(other.outgoingHeader);
         flags = other.flags;
         clock.init(other.clock);

apm-agent-core/src/main/resources/schema/transactions/span.json

@@ -18,6 +18,11 @@
             "description": "ID for the parent (transaction or span), hex encoded 64 random bits",
             "pattern": "^[a-fA-F0-9]{16}$"
         },
+        "transaction_id": {
+            "type": "string",
+            "description": "ID for the transaction this span belongs to, hex encoded 64 random bits",
+            "pattern": "^[a-fA-F0-9]{16}$"
+        },
         "timestamp": {
             "type": ["string", "integer"],
             "description": "Recorded time of the span, UTC based and formatted as YYYY-MM-DDTHH:mm:ss.sssZ"
@@ -87,5 +92,5 @@
             "required": ["id"]
         }
     },
-    "required": ["duration", "name", "type", "timestamp"]
+    "required": ["duration", "name", "type", "timestamp", "transaction_id"]
 }

apm-opentracing/src/test/java/co/elastic/apm/opentracing/OpenTracingBridgeTest.java

@@ -148,6 +148,7 @@ void testCreateNonActiveTransactionAsChildOf() {
         transaction.finish();
         assertThat(reporter.getTransactions()).hasSize(1);
         assertThat(reporter.getSpans()).hasSize(1);
+        assertThat(reporter.getFirstSpan().getTraceContext().getTransactionId().isEmpty()).isFalse();
     }
 
     @Test