#1507 - Fix potential NullPointerException in Jsr303AwarePropertyMetadata.

We now check whether we could really load `@Range`, which is only available from Java Validation 2.0 and newer. Classpaths that only included a 1.x flavor of that would end up with `null` for the loaded class and have that forwarded into a method not accepting `null` values.

Author: odrotbohm

src/main/java/org/springframework/hateoas/mediatype/PropertyUtils.java

@@ -539,7 +539,7 @@ protected String getAnnotatedInputType() {
 	private static class Jsr303AwarePropertyMetadata extends DefaultPropertyMetadata {
 
 		private static final Optional<Class<? extends Annotation>> LENGTH_ANNOTATION;
-		private static final Class<? extends Annotation> URL_ANNOTATION, RANGE_ANNOTATION;
+		private static final @Nullable Class<? extends Annotation> URL_ANNOTATION, RANGE_ANNOTATION;
 		private static final Map<Class<? extends Annotation>, String> TYPE_MAP;
 
 		static {
@@ -609,10 +609,13 @@ public Optional<String> getPattern() {
 		@Override
 		public Long getMin() {
 
-			Optional<Long> attribute = getAnnotationAttribute(RANGE_ANNOTATION, "min", Long.class);
+			if (RANGE_ANNOTATION != null) {
+
+				Optional<Long> attribute = getAnnotationAttribute(RANGE_ANNOTATION, "min", Long.class);
 
-			if (attribute.isPresent()) {
-				return attribute.get();
+				if (attribute.isPresent()) {
+					return attribute.get();
+				}
 			}
 
 			return getAnnotationAttribute(Min.class, "value", Long.class).orElse(null);
@@ -626,10 +629,13 @@ public Long getMin() {
 		@Override
 		public Long getMax() {
 
-			Optional<Long> attribute = getAnnotationAttribute(RANGE_ANNOTATION, "max", Long.class);
+			if (RANGE_ANNOTATION != null) {
+
+				Optional<Long> attribute = getAnnotationAttribute(RANGE_ANNOTATION, "max", Long.class);
 
-			if (attribute.isPresent()) {
-				return attribute.get();
+				if (attribute.isPresent()) {
+					return attribute.get();
+				}
 			}
 
 			return getAnnotationAttribute(Max.class, "value", Long.class).orElse(null);