Merge branch '1.2.x'

Author: snicoll

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

@@ -127,9 +127,12 @@ public boolean process(Set<? extends TypeElement> annotations,
 			RoundEnvironment roundEnv) {
 		this.metadataCollector.processing(roundEnv);
 		Elements elementUtils = this.processingEnv.getElementUtils();
-		for (Element element : roundEnv.getElementsAnnotatedWith(elementUtils
-				.getTypeElement(configurationPropertiesAnnotation()))) {
-			processElement(element);
+		TypeElement annotationType = elementUtils
+				.getTypeElement(configurationPropertiesAnnotation());
+		if (annotationType != null) { // Is @ConfigurationProperties available
+			for (Element element : roundEnv.getElementsAnnotatedWith(annotationType)) {
+				processElement(element);
+			}
 		}
 		if (roundEnv.processingOver()) {
 			writeMetaData();