#361 - Polishing.

Made implementation class package protected to not expose it. Avoid the use of Optional for hot code paths. Removed factory method as we only use the type internally anyway.

Removed test customizations as the discoverer is now just leniently opting out if not ApplicationContext can be found.

Original pull request: #1328.

src/main/java/org/springframework/hateoas/server/mvc/PropertyResolvingMappingDiscoverer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019-2020 the original author or authors.
+ * Copyright 2020 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.
@@ -15,32 +15,31 @@
  */
 package org.springframework.hateoas.server.mvc;
 
-import static java.util.Optional.ofNullable;
+import java.lang.reflect.Method;
+import java.util.Collection;
 
-import org.springframework.core.env.PropertyResolver;
 import org.springframework.hateoas.server.core.MappingDiscoverer;
 import org.springframework.http.HttpMethod;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.web.context.ContextLoader;
-
-import java.lang.reflect.Method;
-import java.util.Collection;
+import org.springframework.web.context.WebApplicationContext;
 
 /**
  * Property resolving adapter of {@link MappingDiscoverer}.
  *
  * @author Lars Michele
+ * @author Oliver Drotbohm
  */
-public class PropertyResolvingMappingDiscoverer implements MappingDiscoverer {
+class PropertyResolvingMappingDiscoverer implements MappingDiscoverer {
 
 	private final MappingDiscoverer delegate;
 
-	private PropertyResolvingMappingDiscoverer(MappingDiscoverer delegate) {
-		this.delegate = delegate;
-	}
+	PropertyResolvingMappingDiscoverer(MappingDiscoverer delegate) {
 
-	public static PropertyResolvingMappingDiscoverer of(MappingDiscoverer delegate) {
-		return new PropertyResolvingMappingDiscoverer(delegate);
+		Assert.notNull(delegate, "Delegate MappingDiscoverer must not be null!");
+
+		this.delegate = delegate;
 	}
 
 	/*
@@ -50,7 +49,7 @@ public class PropertyResolvingMappingDiscoverer implements MappingDiscoverer {
 	@Nullable
 	@Override
 	public String getMapping(Class<?> type) {
-		return ofNullable(delegate.getMapping(type)).map(getPropertyResolver()::resolvePlaceholders).orElse(null);
+		return resolveProperties(delegate.getMapping(type));
 	}
 
 	/*
@@ -60,7 +59,7 @@ public class PropertyResolvingMappingDiscoverer implements MappingDiscoverer {
 	@Nullable
 	@Override
 	public String getMapping(Method method) {
-		return ofNullable(delegate.getMapping(method)).map(getPropertyResolver()::resolvePlaceholders).orElse(null);
+		return resolveProperties(delegate.getMapping(method));
 	}
 
 	/*
@@ -70,7 +69,7 @@ public class PropertyResolvingMappingDiscoverer implements MappingDiscoverer {
 	@Nullable
 	@Override
 	public String getMapping(Class<?> type, Method method) {
-		return ofNullable(delegate.getMapping(type, method)).map(getPropertyResolver()::resolvePlaceholders).orElse(null);
+		return resolveProperties(delegate.getMapping(type, method));
 	}
 
 	/*
@@ -82,7 +81,17 @@ public class PropertyResolvingMappingDiscoverer implements MappingDiscoverer {
 		return delegate.getRequestMethod(type, method);
 	}
 
-	private static PropertyResolver getPropertyResolver() {
-		return ContextLoader.getCurrentWebApplicationContext().getEnvironment();
+	@Nullable
+	private static String resolveProperties(@Nullable String mapping) {
+
+		if (mapping == null) {
+			return mapping;
+		}
+
+		WebApplicationContext context = ContextLoader.getCurrentWebApplicationContext();
+
+		return context == null //
+				? mapping //
+				: context.getEnvironment().resolvePlaceholders(mapping);
 	}
 }

src/main/java/org/springframework/hateoas/server/mvc/WebMvcLinkBuilder.java

@@ -53,7 +53,7 @@ import org.springframework.web.util.UriTemplate;
 public class WebMvcLinkBuilder extends TemplateVariableAwareLinkBuilderSupport<WebMvcLinkBuilder> {
 
 	private static final MappingDiscoverer DISCOVERER = CachingMappingDiscoverer
-			.of(PropertyResolvingMappingDiscoverer.of(new AnnotationMappingDiscoverer(RequestMapping.class)));
+			.of(new PropertyResolvingMappingDiscoverer(new AnnotationMappingDiscoverer(RequestMapping.class)));
 	private static final WebMvcLinkBuilderFactory FACTORY = new WebMvcLinkBuilderFactory();
 	private static final CustomUriTemplateHandler HANDLER = new CustomUriTemplateHandler();