Make detection of nested config more lenient

Closes gh-3454

spring-boot-tools/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/ConfigurationMetadataAnnotationProcessor.java

@@ -337,10 +337,25 @@ public class ConfigurationMetadataAnnotationProcessor extends AbstractProcessor
 		if (hasAnnotation(field, nestedConfigurationPropertyAnnotation())) {
 			return true;
 		}
-		return this.typeUtils.isEnclosedIn(returnType, element)
+		return (isParentTheSame(returnType, element))
 				&& returnType.getKind() != ElementKind.ENUM;
 	}
 
+	private boolean isParentTheSame(Element returnType, TypeElement element) {
+		if (returnType == null || element == null) {
+			return false;
+		}
+		return getTopLevelType(returnType).equals(getTopLevelType(element));
+	}
+
+	private Element getTopLevelType(Element element) {
+		if ((element.getEnclosingElement() == null) ||
+				!(element.getEnclosingElement() instanceof TypeElement)) {
+			return element;
+		}
+		return getTopLevelType(element.getEnclosingElement());
+	}
+
 	private boolean isDeprecated(Element element) {
 		if (isElementDeprecated(element)) {
 			return true;

spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/ConfigurationMetadataAnnotationProcessorTests.java

@@ -65,6 +65,7 @@ import org.springframework.boot.configurationsample.specific.DoubleRegistrationP
 import org.springframework.boot.configurationsample.specific.ExcludedTypesPojo;
 import org.springframework.boot.configurationsample.specific.GenericConfig;
 import org.springframework.boot.configurationsample.specific.InnerClassAnnotatedGetterConfig;
+import org.springframework.boot.configurationsample.specific.InnerClassHierachicalProperties;
 import org.springframework.boot.configurationsample.specific.InnerClassProperties;
 import org.springframework.boot.configurationsample.specific.InnerClassRootConfig;
 import org.springframework.boot.configurationsample.specific.InvalidAccessorProperties;
@@ -348,6 +349,19 @@ public class ConfigurationMetadataAnnotationProcessorTests {
 		assertThat(metadata).isNotEqualTo(Metadata.withGroup("config.fourth"));
 	}
 
+	@Test
+	public void innerClassPropertiesHierachical() throws Exception {
+		ConfigurationMetadata metadata = compile(InnerClassHierachicalProperties.class);
+		assertThat(metadata)
+				.has(Metadata.withGroup("config.foo").ofType(InnerClassHierachicalProperties.Foo.class));
+		assertThat(metadata).has(
+				Metadata.withGroup("config.foo.bar").ofType(InnerClassHierachicalProperties.Bar.class));
+		assertThat(metadata).has(
+				Metadata.withGroup("config.foo.bar.baz").ofType(InnerClassHierachicalProperties.Foo.Baz.class));
+		assertThat(metadata).has(Metadata.withProperty("config.foo.bar.baz.blah"));
+		assertThat(metadata).has(Metadata.withProperty("config.foo.bar.bling"));
+	}
+
 	@Test
 	public void innerClassAnnotatedGetterConfig() throws Exception {
 		ConfigurationMetadata metadata = compile(InnerClassAnnotatedGetterConfig.class);

spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/specific/InnerClassHierachicalProperties.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2012-2017 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.configurationsample.specific;
+
+import org.springframework.boot.configurationsample.ConfigurationProperties;
+
+/**
+ * Demonstrate inner classes end up in metadata regardless of
+ * position in hierarchy and without the use of
+ * {@link org.springframework.boot.configurationsample.NestedConfigurationProperty}.
+ *
+ * @author Madhura Bhave
+ */
+@ConfigurationProperties(prefix = "config")
+public class InnerClassHierachicalProperties {
+
+	private Foo foo;
+
+	public Foo getFoo() {
+		return this.foo;
+	}
+
+	public void setFoo(Foo foo) {
+		this.foo = foo;
+	}
+
+	public static class Foo {
+
+		private Bar bar;
+
+		public Bar getBar() {
+			return this.bar;
+		}
+
+		public void setBar(Bar bar) {
+			this.bar = bar;
+		}
+
+		public static class Baz {
+
+			private String blah;
+
+			public String getBlah() {
+				return this.blah;
+			}
+
+			public void setBlah(String blah) {
+				this.blah = blah;
+			}
+		}
+	}
+
+	public static class Bar {
+
+		private String bling;
+
+		private Foo.Baz baz;
+
+		public String getBling() {
+			return this.bling;
+		}
+
+		public void setBling(String foo) {
+			this.bling = foo;
+		}
+
+		public Foo.Baz getBaz() {
+			return this.baz;
+		}
+
+		public void setBaz(Foo.Baz baz) {
+			this.baz = baz;
+		}
+	}
+
+}