Add boot42-otel module: Spring Boot 4.2.0-RC1 OpenTelemetry conventions, shared OTLP settings and MDC keys vs 4.1.2

boot42-otel/output/01-conventions-metrics-and-spans.txt

@@ -0,0 +1,29 @@
+# 01-conventions-metrics-and-spans  (Spring Boot 4.2.0-RC1, JDK 25)
+
+== management.observations.conventions=(property not set)
+-- meters whose name contains 'http':
+   http.server.requests  [error=none, exception=none, method=GET, outcome=SUCCESS, status=200, uri=/hello/{name}]
+-- span-related strings in the OTLP trace payload (1 request(s)):
+   /hello/ankurJ
+   /hello/{name}z
+   http get /hello/{name}0
+
+== management.observations.conventions=micrometer
+-- meters whose name contains 'http':
+   http.server.requests  [error=none, exception=none, method=GET, outcome=SUCCESS, status=200, uri=/hello/{name}]
+-- span-related strings in the OTLP trace payload (1 request(s)):
+   /hello/ankurJ
+   /hello/{name}z
+   http get /hello/{name}0
+
+== management.observations.conventions=open-telemetry
+-- application FAILED to start
+   NoSuchBeanDefinitionException: No qualifying bean of type 'org.springframework.http.server.observation.ServerRequestObservationConvention' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
+
+== management.observations.conventions=opentelemetry
+-- meters whose name contains 'http':
+   http.server.request.duration  [error.type=none, error=none, http.request.method=GET, http.response.status_code=200, http.route=/hello/{name}, outcome=SUCCESS, url.scheme=http]
+-- span-related strings in the OTLP trace payload (1 request(s)):
+   /hello/ankurJ
+   /hello/{name}J
+   GET /hello/{name}0