Call meta-data processor regardless of annotations

Update ConfigurationMetadataAnnotationProcessor so that it gets called
even if the source code doesn't include any @ConfigurationProperties
items.

See spring-projectsgh-1830

Author: philwebb

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

@@ -39,6 +39,7 @@
 import javax.lang.model.element.TypeElement;
 import javax.lang.model.element.VariableElement;
 import javax.lang.model.type.TypeKind;
+import javax.lang.model.util.Elements;
 import javax.tools.Diagnostic.Kind;
 import javax.tools.FileObject;
 import javax.tools.StandardLocation;
@@ -57,7 +58,7 @@
  * @author Phillip Webb
  * @since 1.2.0
  */
-@SupportedAnnotationTypes({ ConfigurationMetadataAnnotationProcessor.CONFIGURATION_PROPERTIES_ANNOTATION })
+@SupportedAnnotationTypes({ "*" })
 @SupportedSourceVersion(SourceVersion.RELEASE_6)
 public class ConfigurationMetadataAnnotationProcessor extends AbstractProcessor {
 
@@ -103,10 +104,10 @@ private void logWarning(String msg) {
 	@Override
 	public boolean process(Set<? extends TypeElement> annotations,
 			RoundEnvironment roundEnv) {
-		for (TypeElement annotation : annotations) {
-			for (Element element : roundEnv.getElementsAnnotatedWith(annotation)) {
-				processElement(element);
-			}
+		Elements elementUtils = this.processingEnv.getElementUtils();
+		for (Element element : roundEnv.getElementsAnnotatedWith(elementUtils
+				.getTypeElement(configurationPropertiesAnnotation()))) {
+			processElement(element);
 		}
 		if (roundEnv.processingOver()) {
 			writeMetaData(this.metadata);
@@ -290,7 +291,6 @@ private ConfigurationMetadata mergeManualMetadata(ConfigurationMetadata metadata
 			}
 		}
 		catch (IOException ex) {
-			ex.printStackTrace();
 			return metadata;
 		}
 	}

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

@@ -41,9 +41,9 @@
 import org.springframework.boot.configurationsample.specific.InnerClassRootConfig;
 import org.springframework.boot.configurationsample.specific.SimplePojo;
 
+import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.not;
-import static org.hamcrest.Matchers.nullValue;
 import static org.junit.Assert.assertThat;
 import static org.springframework.boot.configurationprocessor.ConfigurationMetadataMatchers.containsGroup;
 import static org.springframework.boot.configurationprocessor.ConfigurationMetadataMatchers.containsProperty;
@@ -63,7 +63,7 @@ public class ConfigurationMetadataAnnotationProcessorTests {
 	public void notAnnotated() throws Exception {
 		ConfigurationMetadata metadata = compile(NotAnnotated.class);
 		assertThat("No config metadata file should have been generated when "
-				+ "no metadata is discovered", metadata, nullValue());
+				+ "no metadata is discovered", metadata.getItems(), empty());
 	}
 
 	@Test
@@ -173,8 +173,7 @@ public void parseCollectionConfig() throws Exception {
 	@Test
 	public void simpleMethodConfig() throws Exception {
 		ConfigurationMetadata metadata = compile(SimpleMethodConfig.class);
-		assertThat(metadata, containsGroup("foo")
-				.fromSource(SimpleMethodConfig.class));
+		assertThat(metadata, containsGroup("foo").fromSource(SimpleMethodConfig.class));
 		assertThat(
 				metadata,
 				containsProperty("foo.name", String.class).fromSource(
@@ -258,7 +257,7 @@ private ConfigurationMetadata compile(Class<?>... types) throws IOException {
 		return processor.getMetadata();
 	}
 
-	@SupportedAnnotationTypes({ TestConfigurationMetadataAnnotationProcessor.CONFIGURATION_PROPERTIES_ANNOTATION })
+	@SupportedAnnotationTypes({ "*" })
 	@SupportedSourceVersion(SourceVersion.RELEASE_6)
 	private static class TestConfigurationMetadataAnnotationProcessor extends
 			ConfigurationMetadataAnnotationProcessor {