Make @PropertyMapping support nested annotations

spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/properties/AnnotationsPropertySource.java

@@ -90,7 +90,7 @@ private void collectProperties(String prefix, SkipPropertyMapping defaultSkip, M
 			}
 		}
 		String name = getName(prefix, attributeMapping, attribute);
-		putProperties(name, value.get(), properties);
+		putProperties(name, skip, value.get(), properties);
 	}
 
 	private String getName(String prefix, MergedAnnotation<?> attributeMapping, Method attribute) {
@@ -118,11 +118,17 @@ private String dotAppend(String prefix, String postfix) {
 		return postfix;
 	}
 
-	private void putProperties(String name, Object value, Map<String, Object> properties) {
+	private void putProperties(String name, SkipPropertyMapping defaultSkip, Object value,
+			Map<String, Object> properties) {
 		if (ObjectUtils.isArray(value)) {
 			Object[] array = ObjectUtils.toObjectArray(value);
 			for (int i = 0; i < array.length; i++) {
-				properties.put(name + "[" + i + "]", array[i]);
+				putProperties(name + "[" + i + "]", defaultSkip, array[i], properties);
+			}
+		}
+		else if (value instanceof MergedAnnotation<?>) {
+			for (Method attribute : ((MergedAnnotation<?>) value).getType().getDeclaredMethods()) {
+				collectProperties(name, defaultSkip, (MergedAnnotation<?>) value, attribute, properties);
 			}
 		}
 		else {

spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/properties/AnnotationsPropertySourceTests.java

@@ -21,6 +21,9 @@
 
 import org.junit.jupiter.api.Test;
 
+import org.springframework.boot.test.autoconfigure.properties.AnnotationsPropertySourceTests.DeeplyNestedAnnotations.Level1;
+import org.springframework.boot.test.autoconfigure.properties.AnnotationsPropertySourceTests.DeeplyNestedAnnotations.Level2;
+import org.springframework.boot.test.autoconfigure.properties.AnnotationsPropertySourceTests.NestedAnnotations.Entry;
 import org.springframework.core.annotation.AliasFor;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -172,6 +175,26 @@ void enumValueNotMapped() {
 		assertThat(source.containsProperty("testenum.value")).isFalse();
 	}
 
+	@Test
+	void nestedAnnotationsMapped() {
+		AnnotationsPropertySource source = new AnnotationsPropertySource(PropertyMappedWithNestedAnnotations.class);
+		assertThat(source.getProperty("testnested")).isNull();
+		assertThat(source.getProperty("testnested.entries[0]")).isNull();
+		assertThat(source.getProperty("testnested.entries[0].value")).isEqualTo("one");
+		assertThat(source.getProperty("testnested.entries[1]")).isNull();
+		assertThat(source.getProperty("testnested.entries[1].value")).isEqualTo("two");
+	}
+
+	@Test
+	void deeplyNestedAnnotationsMapped() {
+		AnnotationsPropertySource source = new AnnotationsPropertySource(
+				PropertyMappedWithDeeplyNestedAnnotations.class);
+		assertThat(source.getProperty("testdeeplynested")).isNull();
+		assertThat(source.getProperty("testdeeplynested.level1")).isNull();
+		assertThat(source.getProperty("testdeeplynested.level1.level2")).isNull();
+		assertThat(source.getProperty("testdeeplynested.level1.level2.value")).isEqualTo("level2");
+	}
+
 	static class NoAnnotation {
 
 	}
@@ -396,4 +419,51 @@ enum EnumItem {
 
 	}
 
+	@Retention(RetentionPolicy.RUNTIME)
+	@PropertyMapping("testnested")
+	@interface NestedAnnotations {
+
+		Entry[] entries();
+
+		@Retention(RetentionPolicy.RUNTIME)
+		@interface Entry {
+
+			String value();
+
+		}
+
+	}
+
+	@NestedAnnotations(entries = { @Entry("one"), @Entry("two") })
+	static class PropertyMappedWithNestedAnnotations {
+
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	@PropertyMapping("testdeeplynested")
+	@interface DeeplyNestedAnnotations {
+
+		Level1 level1();
+
+		@Retention(RetentionPolicy.RUNTIME)
+		@interface Level1 {
+
+			Level2 level2();
+
+		}
+
+		@Retention(RetentionPolicy.RUNTIME)
+		@interface Level2 {
+
+			String value();
+
+		}
+
+	}
+
+	@DeeplyNestedAnnotations(level1 = @Level1(level2 = @Level2("level2")))
+	static class PropertyMappedWithDeeplyNestedAnnotations {
+
+	}
+
 }