feat: Enhance _encode_value in OpenTelemetry exporter to handle None …

…values as strings (open-telemetry#4392)

exporter/opentelemetry-exporter-otlp-proto-common/src/opentelemetry/exporter/otlp/proto/common/_internal/__init__.py

@@ -81,6 +81,8 @@ def _encode_value(value: Any) -> PB2AnyValue:
         return PB2AnyValue(
             array_value=PB2ArrayValue(values=[_encode_value(v) for v in value])
         )
+    if value is None:
+        return PB2AnyValue(string_value="")
     elif isinstance(value, Mapping):
         return PB2AnyValue(
             kvlist_value=PB2KeyValueList(

exporter/opentelemetry-exporter-otlp-proto-common/tests/test_log_encoder.py

@@ -63,6 +63,18 @@ def test_encode_no_body(self):
 
         self.assertEqual(encode_logs(sdk_logs), expected_encoding)
 
+    def test_encode_body_dict_value_has_none(self):
+        sdk_logs, expected_encoding = self.get_test_logs()
+        for log in sdk_logs:
+            log.log_record.body = {"key": None}
+
+        for resource_log in expected_encoding.resource_logs:
+            for scope_log in resource_log.scope_logs:
+                for log_record in scope_log.log_records:
+                    log_record.body.ClearField("string_value")
+
+        self.assertEqual(encode_logs(sdk_logs), expected_encoding)
+
     def test_dropped_attributes_count(self):
         sdk_logs = self._get_test_logs_dropped_attributes()
         encoded_logs = encode_logs(sdk_logs)