Auto-configure OtlpHttpSpanExporter only if property is set

- Remove the default value of 'management.otlp.tracing.endpoint'

Closes gh-35596

Author: mhalbritter

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/otlp/OtlpAutoConfiguration.java

@@ -30,6 +30,7 @@
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 
@@ -45,6 +46,7 @@
  * define an {@link OtlpGrpcSpanExporter} and this auto-configuration will back off.
  *
  * @author Jonatan Ivanov
+ * @author Moritz Halbritter
  * @since 3.1.0
  */
 @AutoConfiguration
@@ -56,6 +58,7 @@ public class OtlpAutoConfiguration {
 	@Bean
 	@ConditionalOnMissingBean(value = OtlpHttpSpanExporter.class,
 			type = "io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporter")
+	@ConditionalOnProperty(prefix = "management.otlp.tracing", name = "endpoint")
 	OtlpHttpSpanExporter otlpHttpSpanExporter(OtlpProperties properties) {
 		OtlpHttpSpanExporterBuilder builder = OtlpHttpSpanExporter.builder()
 			.setEndpoint(properties.getEndpoint())

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/otlp/OtlpProperties.java

@@ -34,7 +34,7 @@ public class OtlpProperties {
 	/**
 	 * URL to the OTel collector's HTTP API.
 	 */
-	private String endpoint = "http://localhost:4318/v1/traces";
+	private String endpoint;
 
 	/**
 	 * Call timeout for the OTel Collector to process an exported batch of data. This

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/tracing/otlp/OtlpAutoConfigurationTests.java

@@ -33,16 +33,23 @@
  * Tests for {@link OtlpAutoConfiguration}.
  *
  * @author Jonatan Ivanov
+ * @author Moritz Halbritter
  */
 class OtlpAutoConfigurationTests {
 
 	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
 		.withConfiguration(AutoConfigurations.of(OtlpAutoConfiguration.class));
 
+	@Test
+	void shouldNotSupplyBeansIfPropertyIsNotSet() {
+		this.contextRunner.run((context) -> assertThat(context).doesNotHaveBean(OtlpHttpSpanExporter.class));
+	}
+
 	@Test
 	void shouldSupplyBeans() {
-		this.contextRunner.run((context) -> assertThat(context).hasSingleBean(OtlpHttpSpanExporter.class)
-			.hasSingleBean(SpanExporter.class));
+		this.contextRunner.withPropertyValues("management.otlp.tracing.endpoint=http://localhost:4318/v1/traces")
+			.run((context) -> assertThat(context).hasSingleBean(OtlpHttpSpanExporter.class)
+				.hasSingleBean(SpanExporter.class));
 	}
 
 	@Test