[connector/spanmetrics] Fix delta span metrics (open-telemetry#40148)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description
Fixes bug causing calls count to always be 0 when using delta
aggregation temporality (see linked issue).

This PR adds a check for the temporality used so that we only overwrite
the first value for cumulative metrics only.

<!-- Issue number (e.g. open-telemetry#1234) or full URL to issue, if applicable. -->
#### Link to tracking issue
Fixes
open-telemetry#40139

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---------

Co-authored-by: Sean Marciniak <[email protected]>

Author: 2 people

.chloggen/jsonlsy_fix-delta-spanmetrics.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: 'bug_fix'
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: 'spanmetricsconnector'
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: 'Fix bug causing span metrics calls count to be always 0 when using delta temporality'
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [40139]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

connector/spanmetricsconnector/connector_test.go

@@ -190,7 +190,7 @@ func verifyConsumeMetricsInput(tb testing.TB, input pmetric.Metrics, expectedTem
 			dp := callsDps.At(dpi)
 			expectIntValue := numCumulativeConsumptions
 			// this calls init value is 0 for the first Consumption.
-			if numCumulativeConsumptions == 1 {
+			if expectedTemporality == pmetric.AggregationTemporalityCumulative && numCumulativeConsumptions == 1 {
 				expectIntValue = 0
 			}
 			assert.Equal(tb,

connector/spanmetricsconnector/internal/metrics/metrics.go

@@ -391,7 +391,7 @@ func (m *SumMetrics) BuildMetrics(
 		startTimeStamp := startTimeStampGenerator(k, s.startTimestamp)
 		dp.SetStartTimestamp(startTimeStamp)
 		dp.SetTimestamp(timestamp)
-		if s.isFirst {
+		if temporality == pmetric.AggregationTemporalityCumulative && s.isFirst {
 			dp.SetIntValue(0)
 			s.isFirst = false
 		} else {