MessageBodyWorker comparator needs to handle Object differently.

Object is used as the furthest type, there can't be anything farther than that.

Change-Id: Ib57c08dfe30a368974600a0f6cc17bd1a271d5f1

Author: pavelbucek

core-common/src/main/java/org/glassfish/jersey/message/internal/MessageBodyFactory.java

@@ -435,11 +435,18 @@ private Iterator<Class<?>> getClassHierarchyIterator(final Class<?> classParam)
             final ArrayList<Class<?>> classes = new ArrayList<>();
             final LinkedList<Class<?>> unprocessed = new LinkedList<>();
 
+            // Object is special - needs to be always the furthest type.
+            boolean objectFound = false;
+
             unprocessed.add(classParam);
             while (!unprocessed.isEmpty()) {
                 final Class<?> clazz = unprocessed.removeFirst();
 
-                classes.add(clazz);
+                if (Object.class.equals(clazz)) {
+                    objectFound = true;
+                } else {
+                    classes.add(clazz);
+                }
                 unprocessed.addAll(Arrays.asList(clazz.getInterfaces()));
 
                 final Class<?> superclazz = clazz.getSuperclass();
@@ -448,6 +455,10 @@ private Iterator<Class<?>> getClassHierarchyIterator(final Class<?> classParam)
                 }
             }
 
+            if (objectFound) {
+                classes.add(Object.class);
+            }
+
             return classes.iterator();
         }
     }

tests/e2e/src/test/java/org/glassfish/jersey/tests/e2e/common/MessageBodyWriterObjectDistanceTest.java

@@ -0,0 +1,148 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Copyright (c) 2017 Oracle and/or its affiliates. All rights reserved.
+ *
+ * The contents of this file are subject to the terms of either the GNU
+ * General Public License Version 2 only ("GPL") or the Common Development
+ * and Distribution License("CDDL") (collectively, the "License").  You
+ * may not use this file except in compliance with the License.  You can
+ * obtain a copy of the License at
+ * http://glassfish.java.net/public/CDDL+GPL_1_1.html
+ * or packager/legal/LICENSE.txt.  See the License for the specific
+ * language governing permissions and limitations under the License.
+ *
+ * When distributing the software, include this License Header Notice in each
+ * file and include the License file at packager/legal/LICENSE.txt.
+ *
+ * GPL Classpath Exception:
+ * Oracle designates this particular file as subject to the "Classpath"
+ * exception as provided by Oracle in the GPL Version 2 section of the License
+ * file that accompanied this code.
+ *
+ * Modifications:
+ * If applicable, add the following below the License Header, with the fields
+ * enclosed by brackets [] replaced by your own identifying information:
+ * "Portions Copyright [year] [name of copyright owner]"
+ *
+ * Contributor(s):
+ * If you wish your version of this file to be governed by only the CDDL or
+ * only the GPL Version 2, indicate your decision by adding "[Contributor]
+ * elects to include this software in this distribution under the [CDDL or GPL
+ * Version 2] license."  If you don't indicate a single choice of license, a
+ * recipient has the option to distribute your version of this file under
+ * either the CDDL, the GPL Version 2 or to extend the choice of license to
+ * its licensees as provided above.  However, if you add GPL Version 2 code
+ * and therefore, elected the GPL Version 2 license, then the option applies
+ * only if the new code is made subject to such option by the copyright
+ * holder.
+ */
+
+package org.glassfish.jersey.tests.e2e.common;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Type;
+
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+import javax.ws.rs.Produces;
+import javax.ws.rs.WebApplicationException;
+import javax.ws.rs.core.Application;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.MultivaluedMap;
+import javax.ws.rs.ext.MessageBodyWriter;
+import javax.ws.rs.ext.Provider;
+
+import org.glassfish.jersey.server.ResourceConfig;
+import org.glassfish.jersey.test.JerseyTest;
+
+import org.junit.Test;
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Object.class needs special handling when computing type distance - it should be always further than any other
+ * implemented interface.
+ *
+ * @author Pavel Bucek (pavel.bucek at oracle.com)
+ */
+@SuppressWarnings("WeakerAccess")
+public class MessageBodyWriterObjectDistanceTest extends JerseyTest {
+
+    public interface InterfaceA {
+
+    }
+
+    public interface InterfaceB extends InterfaceA {
+
+    }
+
+    @Provider
+    @Produces("application/test")
+    public static class ObjectWriter implements MessageBodyWriter<Object> {
+
+        @Override
+        public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
+            return true;
+        }
+
+        @Override
+        public long getSize(Object o, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
+            return -1;
+        }
+
+        @Override
+        public void writeTo(Object o, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType,
+                            MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream) throws IOException,
+                WebApplicationException {
+            entityStream.write("object".getBytes("UTF-8"));
+        }
+    }
+
+    @Provider
+    @Produces("application/test")
+    public static class InterfaceAWriter implements MessageBodyWriter<InterfaceA> {
+        @Override
+        public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
+            return InterfaceA.class.isAssignableFrom(type);
+        }
+
+        @Override
+        public long getSize(InterfaceA interfaceA, Class<?> type, Type genericType, Annotation[] annotations,
+                            MediaType mediaType) {
+            return -1;
+        }
+
+        @Override
+        public void writeTo(InterfaceA interfaceA, Class<?> type, Type genericType, Annotation[] annotations,
+                            MediaType mediaType, MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream)
+                throws IOException, WebApplicationException {
+            entityStream.write(InterfaceA.class.getSimpleName().getBytes("UTF-8"));
+        }
+    }
+
+    @Path("resource")
+    public static class Resource {
+
+        @GET
+        @Produces("application/test")
+        public InterfaceB getStringModel() {
+            return new InterfaceB() {
+            };
+        }
+    }
+
+    @Override
+    protected Application configure() {
+        return new ResourceConfig(Resource.class)
+                .register(ObjectWriter.class)
+                .register(InterfaceAWriter.class);
+    }
+
+    @Test
+    public void testMessageBodyWriterObjectDistance() throws Exception {
+        assertEquals(InterfaceA.class.getSimpleName(),
+                     target().path("resource").request("application/test").get(String.class));
+    }
+}