Fix SubclassClassifier so it recognizes multiple parents

Prior to this fix interfaces with multiple parents were not
recognized.

src/main/java/org/springframework/classify/SubclassClassifier.java

@@ -16,10 +16,14 @@
 package org.springframework.classify;
 
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 
+import org.springframework.util.ClassUtils;
+
 /**
  * A {@link Classifier} for a parameterised object type based on a map. Classifies objects
  * according to their inheritance relation with the supplied type map. If the object to be
@@ -58,7 +62,7 @@ public class SubclassClassifier<T, C> implements Classifier<T, C> {
 	/**
 	 * Create a {@link SubclassClassifier} with supplied default value.
 	 * @param defaultValue the default value
-	 * @param typeMap the map of types
+	 * @param typeMap      the map of types
 	 */
 	public SubclassClassifier(Map<Class<? extends T>, C> typeMap, C defaultValue) {
 		super();
@@ -115,7 +119,7 @@ public class SubclassClassifier<T, C> implements Classifier<T, C> {
 		if (value == null) {
 			for (Class<?> cls = exceptionClass; !cls.equals(Object.class)
 					&& value == null; cls = cls.getSuperclass()) {
-				for (Class<?> ifc : cls.getInterfaces()) {
+				for (Class<?> ifc : getAllInterfacesForClass(cls)) {
 					value = this.classified.get(ifc);
 					if (value != null) {
 						break;
@@ -148,4 +152,16 @@ public class SubclassClassifier<T, C> implements Classifier<T, C> {
 		return this.classified;
 	}
 
+	private static Set<Class<?>> getAllInterfacesForClass(Class<?> cls) {
+		Set<Class<?>> set = new HashSet<Class<?>>();
+		getAllInterfacesForClass(cls, set);
+		return set;
+	}
+
+	private static void getAllInterfacesForClass(Class<?> cls, Set<Class<?>> set) {
+		set.addAll(ClassUtils.getAllInterfacesForClassAsSet(cls));
+		for (Class<?> ifc : cls.getInterfaces()) {
+			getAllInterfacesForClass(ifc, set);
+		}
+	}
 }

src/test/java/org/springframework/classify/SubclassClassifierTests.java

@@ -16,13 +16,14 @@
 
 package org.springframework.classify;
 
+import static org.junit.Assert.assertEquals;
+
 import java.util.Collections;
+import java.util.concurrent.Callable;
 import java.util.function.Supplier;
 
 import org.junit.Test;
 
-import static org.junit.Assert.assertEquals;
-
 public class SubclassClassifierTests {
 
 	@Test
@@ -33,6 +34,14 @@ public class SubclassClassifierTests {
 		assertEquals("foo", classifier.classify(new Foo()));
 	}
 
+	@Test
+	public void testClassifyMultipleInterface() {
+		SubclassClassifier<Object, String> classifier = new SubclassClassifier<Object, String>();
+		classifier.setTypeMap(
+				Collections.<Class<?>, String>singletonMap(Supplier.class, "foo"));
+		assertEquals("foo", classifier.classify(new Spam()));
+	}
+
 	@Test
 	public void testClassifyInterfaceOfParent() {
 		SubclassClassifier<Object, String> classifier = new SubclassClassifier<Object, String>();
@@ -54,4 +63,22 @@ public class SubclassClassifierTests {
 
 	}
 
+	public class Spam implements Mixer {
+
+		@Override
+		public String get() {
+			return "foo";
+		}
+
+		@Override
+		public String call() throws Exception {
+			return "bar";
+		}
+
+	}
+
+	public static interface Mixer extends Supplier<String>, Callable<String> {
+
+	}
+
 }