Appending spans should store a copy of the span

Signed-off-by: Juraci Paixão Kröhling <juraci@kroehling.de>

processor/groupbytraceprocessor/storage_memory.go

@@ -48,8 +48,10 @@ func (st *memoryStorage) createOrAppend(traceID pdata.TraceID, trace pdata.Resou
 	if ok {
 		// we have a trace already, append the spans
 		for i := 0; i < trace.InstrumentationLibrarySpans().Len(); i++ {
-			spans := trace.InstrumentationLibrarySpans().At(i)
-			existing.InstrumentationLibrarySpans().Append(&spans)
+			newSpans := pdata.NewInstrumentationLibrarySpans()
+			orig := trace.InstrumentationLibrarySpans().At(i)
+			orig.CopyTo(newSpans)
+			existing.InstrumentationLibrarySpans().Append(&newSpans)
 		}
 	} else {
 		newTrace := pdata.NewResourceSpans()

processor/groupbytraceprocessor/storage_memory_test.go

@@ -116,6 +116,7 @@ func TestMemoryAppendSpans(t *testing.T) {
 
 	secondSpan := pdata.NewSpan()
 	secondSpan.InitEmpty()
+	secondSpan.SetName("second-name")
 	secondSpan.SetTraceID(traceID)
 	secondSpan.SetSpanID(pdata.NewSpanID([]byte{5, 6, 7, 8}))
 
@@ -140,9 +141,17 @@ func TestMemoryAppendSpans(t *testing.T) {
 	err := st.createOrAppend(traceID, secondBatch)
 	require.NoError(t, err)
 
+	// override something in the second span, to make sure we are storing a copy
+	secondSpan.SetName("changed-second-name")
+
 	// verify
 	retrieved, err := st.get(traceID)
 	require.NoError(t, err)
+	assert.Equal(t, "second-name", retrieved.InstrumentationLibrarySpans().At(1).Spans().At(0).Name())
+
+	// now that we checked that the secondSpan change here didn't have an effect, revert
+	// so that we can compare the that everything else has the same value
+	secondSpan.SetName("second-name")
 	assert.Equal(t, expected, retrieved)
 }