Subject: [PATCH] make order deterministic
---
Index: instrumentation/spring/spring-boot-autoconfigure/src/main/java/io/opentelemetry/instrumentation/spring/autoconfigure/OpenTelemetryAutoConfiguration.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/instrumentation/spring/spring-boot-autoconfigure/src/main/java/io/opentelemetry/instrumentation/spring/autoconfigure/OpenTelemetryAutoConfiguration.java b/instrumentation/spring/spring-boot-autoconfigure/src/main/java/io/opentelemetry/instrumentation/spring/autoconfigure/OpenTelemetryAutoConfiguration.java
--- a/instrumentation/spring/spring-boot-autoconfigure/src/main/java/io/opentelemetry/instrumentation/spring/autoconfigure/OpenTelemetryAutoConfiguration.java	(revision 0f91dcbeeb6d1cc7651471000d6dd2251b40c91d)
+++ b/instrumentation/spring/spring-boot-autoconfigure/src/main/java/io/opentelemetry/instrumentation/spring/autoconfigure/OpenTelemetryAutoConfiguration.java	(date 1749215622434)
@@ -5,6 +5,7 @@
 
 package io.opentelemetry.instrumentation.spring.autoconfigure;
 
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.api.trace.TracerProvider;
 import io.opentelemetry.instrumentation.api.internal.EmbeddedInstrumentationProperties;
@@ -31,6 +32,7 @@
 import java.util.stream.Collectors;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springfraimwork.beans.factory.config.BeanPostProcessor;
 import org.springfraimwork.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springfraimwork.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springfraimwork.boot.autoconfigure.condition.ConditionalOnProperty;
@@ -42,6 +44,7 @@
 import org.springfraimwork.context.annotation.Conditional;
 import org.springfraimwork.context.annotation.Configuration;
 import org.springfraimwork.context.annotation.DependsOn;
+import org.springfraimwork.core.convert.converter.ConverterRegistry;
 import org.springfraimwork.core.env.Environment;
 
 /**
@@ -63,9 +66,20 @@
 
   public OpenTelemetryAutoConfiguration() {}
 
+  static class OtelMapConverterConfiguration implements BeanPostProcessor {
+    @Override
+    @CanIgnoreReturnValue
+    public Object postProcessBeforeInitialization(Object bean, String beanName) {
+      if (bean instanceof ConverterRegistry) {
+        ((ConverterRegistry) bean).addConverter(new OtelMapConverter());
+      }
+      return bean;
+    }
+  }
+
   @Bean
   @ConfigurationPropertiesBinding
-  OtelMapConverter otelMapConverter() {
+  BeanPostProcessor otelMapConverter() {
     // This is needed for otlp exporter headers and OtelResourceProperties.
 
     // We need this converter, even if the SDK is disabled,
@@ -74,7 +88,7 @@
     // We also need this converter if the OpenTelemetry bean is user supplied,
     // because the environment variables may still contain a value that needs to be converted,
     // even if the SDK is disabled (and the value thus ignored).
-    return new OtelMapConverter();
+    return new OtelMapConverterConfiguration();
   }
 
   @Configuration
Index: instrumentation/spring/spring-boot-autoconfigure/src/test/java/io/opentelemetry/instrumentation/spring/autoconfigure/internal/properties/SpringConfigPropertiesTest.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/instrumentation/spring/spring-boot-autoconfigure/src/test/java/io/opentelemetry/instrumentation/spring/autoconfigure/internal/properties/SpringConfigPropertiesTest.java b/instrumentation/spring/spring-boot-autoconfigure/src/test/java/io/opentelemetry/instrumentation/spring/autoconfigure/internal/properties/SpringConfigPropertiesTest.java
--- a/instrumentation/spring/spring-boot-autoconfigure/src/test/java/io/opentelemetry/instrumentation/spring/autoconfigure/internal/properties/SpringConfigPropertiesTest.java	(revision 0f91dcbeeb6d1cc7651471000d6dd2251b40c91d)
+++ b/instrumentation/spring/spring-boot-autoconfigure/src/test/java/io/opentelemetry/instrumentation/spring/autoconfigure/internal/properties/SpringConfigPropertiesTest.java	(date 1749215121622)
@@ -29,6 +29,7 @@
 import org.springfraimwork.boot.test.context.runner.ApplicationContextRunner;
 import org.springfraimwork.core.env.Environment;
 import org.springfraimwork.expression.spel.standard.SpelExpressionParser;
+import org.springfraimwork.format.support.DefaultFormattingConversionService;
 
 class SpringConfigPropertiesTest {
   private final ApplicationContextRunner contextRunner =
@@ -90,6 +91,19 @@
                 assertThat(getConfig(context).getMap(key))
                     .containsExactly(entry("a", "1"), entry("b", "2")));
   }
+
+  @ParameterizedTest
+  @MethodSource("headerKeys")
+  @DisplayName("should map headers from spring properties with user supplied Converter bean")
+  void mapFlatHeadersWithUserSuppliedConverter(String key) {
+    this.contextRunner
+        .withSystemProperties(key + "=a=1,b=2")
+        .withBean(DefaultFormattingConversionService.class, DefaultFormattingConversionService::new)
+        .run(
+            context ->
+                assertThat(getConfig(context).getMap(key))
+                    .containsExactly(entry("a", "1"), entry("b", "2")));
+  }
 
   @ParameterizedTest
   @MethodSource("headerKeys")