[pkg/otlp/metrics] Fix empty exponential histogram mapping

.chloggen/mx-psi_emptyexpohisto.yaml

@@ -0,0 +1,16 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component (e.g. pkg/quantile)
+component: pkg/otlp/metrics
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Empty OTLP Exponential Histograms are now dropped instead of causing a crash
+
+# The PR related to this change
+issues: [158]
+
+# (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:

pkg/otlp/metrics/exponential_histograms_translator.go

@@ -151,6 +151,7 @@ func (t *Translator) mapExponentialHistogramMetrics(
 				zap.String("metric name", dims.name),
 				zap.Error(err),
 			)
+			continue
 		}
 
 		if histInfo.ok {

pkg/otlp/metrics/histograms_test.go

@@ -173,6 +173,19 @@ func TestExponentialHistogramTranslatorOptions(t *testing.T) {
 			expectedUnknownMetricType: 1,
 			expectedUnsupportedAggregationTemporality: 1,
 		},
+		{
+			// https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/26103
+			name:     "empty-delta-issue-26103",
+			otlpfile: "testdata/otlpdata/histogram/empty-delta-exponential.json",
+			ddogfile: "testdata/datadogdata/histogram/empty-delta-exponential.json",
+		},
+		{
+			// https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/26103
+			name:     "empty-cumulative-issue-26103",
+			otlpfile: "testdata/otlpdata/histogram/empty-cumulative-exponential.json",
+			ddogfile: "testdata/datadogdata/histogram/empty-cumulative-exponential.json",
+			expectedUnsupportedAggregationTemporality: 1,
+		},
 		{
 			name:     "resource-attributes-as-tags",
 			otlpfile: "testdata/otlpdata/histogram/simple-exponential.json",

pkg/otlp/metrics/testdata/datadogdata/histogram/empty-cumulative-exponential.json

@@ -0,0 +1 @@
+{}

pkg/otlp/metrics/testdata/datadogdata/histogram/empty-delta-exponential.json

@@ -0,0 +1 @@
+{}

pkg/otlp/metrics/testdata/otlpdata/histogram/empty-cumulative-exponential.json

@@ -0,0 +1,38 @@
+{
+    "resourceMetrics":[
+      {
+        "resource":{
+
+        },
+        "scopeMetrics":[
+          {
+            "scope":{
+
+            },
+            "metrics":[
+              {
+                "name": "empty.exponential.cumulative.histogram",
+                "exponentialHistogram":{
+                  "dataPoints":[
+                    {
+                      "startTimeUnixNano":"1693305960229586125",
+                      "timeUnixNano":"1693305970229586125",
+                      "sum":0,
+                      "scale":4,
+                      "positive":{
+
+                      },
+                      "negative":{
+
+                      }
+                    }
+                  ],
+                  "aggregationTemporality":2
+                }
+              }
+            ]
+          }
+        ]
+      }
+    ]
+  }

pkg/otlp/metrics/testdata/otlpdata/histogram/empty-delta-exponential.json

@@ -0,0 +1,38 @@
+{
+    "resourceMetrics":[
+      {
+        "resource":{
+
+        },
+        "scopeMetrics":[
+          {
+            "scope":{
+
+            },
+            "metrics":[
+              {
+                "name": "empty.exponential.delta.histogram",
+                "exponentialHistogram":{
+                  "dataPoints":[
+                    {
+                      "startTimeUnixNano":"1693305960229586125",
+                      "timeUnixNano":"1693305970229586125",
+                      "sum":0,
+                      "scale":4,
+                      "positive":{
+
+                      },
+                      "negative":{
+
+                      }
+                    }
+                  ],
+                  "aggregationTemporality":1
+                }
+              }
+            ]
+          }
+        ]
+      }
+    ]
+  }