OnClassCondition report should only include relevant condition

Closes gh-11086

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/OnClassCondition.java

@@ -158,7 +158,7 @@ class OnClassCondition extends SpringBootCondition
 		MultiValueMap<String, Object> attributes = metadata
 				.getAllAnnotationAttributes(annotationType.getName(), true);
 		if (attributes == null) {
-			return Collections.emptyList();
+			return null;
 		}
 		List<String> candidates = new ArrayList<>();
 		addAll(candidates, attributes.get("value"));

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/condition/ConditionalOnClassTests.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.autoconfigure.condition;
 
+import java.util.Collection;
+
 import org.junit.Test;
 
 import org.springframework.boot.test.context.assertj.AssertableApplicationContext;
@@ -68,6 +70,20 @@ public class ConditionalOnClassTests {
 				.run(this::hasBarBean);
 	}
 
+	@Test
+	public void onClassConditionOutputShouldNotContainConditionalOnMissingClassInMessage() {
+		this.contextRunner.withUserConfiguration(BasicConfiguration.class)
+				.run((context) -> {
+					Collection<ConditionEvaluationReport.ConditionAndOutcomes> conditionAndOutcomes = ConditionEvaluationReport
+							.get(context.getSourceApplicationContext().getBeanFactory())
+							.getConditionAndOutcomesBySource().values();
+					String message = conditionAndOutcomes.iterator().next().iterator()
+							.next().getOutcome().getMessage();
+					assertThat(message).doesNotContain(
+							"@ConditionalOnMissingClass did not find unwanted class");
+				});
+	}
+
 	private void hasBarBean(AssertableApplicationContext context) {
 		assertThat(context).hasBean("bar");
 		assertThat(context.getBean("bar")).isEqualTo("bar");