Document double observations when using @timed etc.

Closes gh-44037

Author: mhalbritter

buildSrc/src/main/resources/org/springframework/boot/build/antora/antora-asciidoc-attributes.properties

@@ -27,6 +27,7 @@ url-gradle-dsl=https://docs.gradle.org/current/dsl
 url-gradle-javadoc=https://docs.gradle.org/current/javadoc
 url-kotlin-docs-kotlin-plugin={url-kotlin-docs}/using-gradle.html
 url-micrometer-docs-concepts={url-micrometer-docs}/concepts
+url-micrometer-docs-observation={url-micrometer-docs}/observation
 url-micrometer-docs-implementations={url-micrometer-docs}/implementations
 url-native-build-tools-docs=https://graalvm.github.io/native-build-tools/{version-native-build-tools}
 url-native-build-tools-docs-gradle-plugin={url-native-build-tools-docs}/gradle-plugin.html

spring-boot-project/spring-boot-docs/src/docs/antora/modules/ROOT/pages/redirect.adoc

@@ -1192,8 +1192,8 @@
 * xref:reference:actuator/metrics.adoc#actuator.metrics.supported.system[#actuator.metrics.supported.system]
 * xref:reference:actuator/metrics.adoc#actuator.metrics.supported.system[#production-ready-metrics-system]
 * xref:reference:actuator/metrics.adoc#actuator.metrics.supported.tasks[#actuator.metrics.supported.tasks]
-* xref:reference:actuator/metrics.adoc#actuator.metrics.supported.timed-annotation[#actuator.metrics.supported.timed-annotation]
-* xref:reference:actuator/metrics.adoc#actuator.metrics.supported.timed-annotation[#production-ready-metrics-timed-annotation]
+* xref:reference:actuator/observability.adoc#actuator.observability.annotations[#actuator.metrics.supported.timed-annotation]
+* xref:reference:actuator/observability.adoc#actuator.observability.annotations[#production-ready-metrics-timed-annotation]
 * xref:reference:actuator/metrics.adoc#actuator.metrics.supported.tomcat[#actuator.metrics.supported.tomcat]
 * xref:reference:actuator/metrics.adoc#actuator.metrics.supported.tomcat[#production-ready-metrics-tomcat]
 * xref:reference:actuator/metrics.adoc#actuator.metrics.supported[#actuator.metrics.supported]

spring-boot-project/spring-boot-docs/src/docs/antora/modules/reference/pages/actuator/metrics.adoc

@@ -1124,14 +1124,6 @@ Metrics for Jetty's javadoc:org.eclipse.jetty.server.Connector[] instances are b
 
 
 
-[[actuator.metrics.supported.timed-annotation]]
-=== @Timed Annotation Support
-
-To enable scanning of javadoc:io.micrometer.core.annotation.Timed[format=annotation] annotations, you will need to set the configprop:management.observations.annotations.enabled[] property to `true`.
-Please refer to the {url-micrometer-docs-concepts}/timers.html#_the_timed_annotation[Micrometer documentation].
-
-
-
 [[actuator.metrics.supported.redis]]
 === Redis Metrics
 

spring-boot-project/spring-boot-docs/src/docs/antora/modules/reference/pages/actuator/observability.adoc

@@ -104,5 +104,9 @@ The next sections will provide more details about logging, metrics and traces.
 [[actuator.observability.annotations]]
 == Micrometer Observation Annotations support
 
-To enable scanning of metrics and tracing annotations like javadoc:io.micrometer.core.annotation.Timed[format=annotation], javadoc:io.micrometer.core.annotation.Counted[format=annotation], javadoc:io.micrometer.core.aop.MeterTag[format=annotation] and javadoc:io.micrometer.tracing.annotation.NewSpan[format=annotation] annotations, you will need to set the configprop:management.observations.annotations.enabled[] property to `true`.
-This feature is supported Micrometer directly. Please refer to the {url-micrometer-docs-concepts}/timers.html#_the_timed_annotation[Micrometer] and {url-micrometer-tracing-docs}/api.html#_aspect_oriented_programming[Micrometer Tracing] reference docs.
+To enable scanning of observability annotations like javadoc:io.micrometer.observation.annotation.Observed[format=annotation], javadoc:io.micrometer.core.annotation.Timed[format=annotation], javadoc:io.micrometer.core.annotation.Counted[format=annotation], javadoc:io.micrometer.core.aop.MeterTag[format=annotation] and javadoc:io.micrometer.tracing.annotation.NewSpan[format=annotation] annotations, you need to set the configprop:management.observations.annotations.enabled[] property to `true`.
+This feature is supported by Micrometer directly.
+Please refer to the {url-micrometer-docs-concepts}/timers.html#_the_timed_annotation[Micrometer], {url-micrometer-docs-observation}/components.html#micrometer-observation-annotations[Micrometer Observation] and {url-micrometer-tracing-docs}/api.html#_aspect_oriented_programming[Micrometer Tracing] reference docs.
+
+NOTE: When you annotate methods or classes which are already instrumented (for example xref:reference:actuator/metrics.adoc#actuator.metrics.supported.spring-data-repository[Spring Data repositories] or xref:reference:actuator/metrics.adoc#actuator.metrics.supported.spring-mvc[Spring MVC controllers]), you will get duplicate observations.
+In that case you can either disable the automatic instrumentation using xref:reference:actuator/observability.adoc#actuator.observability.preventing-observations[properties] or an javadoc:io.micrometer.observation.ObservationPredicate[] and rely on your annotations, or you can remove your annotation.