Ability to disable the automatic Logback appender addition

Author: jeanbisutti

instrumentation/spring/spring-boot-autoconfigure/src/main/java/io/opentelemetry/instrumentation/spring/autoconfigure/instrumentation/logging/LogbackAppenderApplicationListener.java

@@ -63,12 +63,25 @@ public void onApplicationEvent(ApplicationEvent event) {
       if (existingOpenTelemetryAppender.isPresent()) {
         reInitializeOpenTelemetryAppender(
             existingOpenTelemetryAppender, applicationEnvironmentPreparedEvent);
-      } else {
+      } else if (isLogbackAppenderAddable(applicationEnvironmentPreparedEvent)) {
         addOpenTelemetryAppender(applicationEnvironmentPreparedEvent);
       }
     }
   }
 
+  private static boolean isLogbackAppenderAddable(
+      ApplicationEnvironmentPreparedEvent applicationEnvironmentPreparedEvent) {
+    Boolean otelSdkDisableProperty =
+        evaluateBooleanProperty(applicationEnvironmentPreparedEvent, "otel.sdk.disabled");
+    Boolean logbackInstrumentationEnabledProperty =
+        evaluateBooleanProperty(
+            applicationEnvironmentPreparedEvent, "otel.instrumentation.logback-appender.enabled");
+    return otelSdkDisableProperty == null
+        || !otelSdkDisableProperty.booleanValue()
+        || logbackInstrumentationEnabledProperty == null
+        || logbackInstrumentationEnabledProperty.booleanValue();
+  }
+
   private static void reInitializeOpenTelemetryAppender(
       Optional<OpenTelemetryAppender> existingOpenTelemetryAppender,
       ApplicationEnvironmentPreparedEvent applicationEnvironmentPreparedEvent) {