#62 - Added support for application/vnd.error+(json|xml).

Introduced representation models for the application/vnd.error media type as specified in [0]. Added default mapping annotations to get it rendered in XML (via JAXB), and JSON (via Jackson 1 and 2).

[0] https://github.com/blongden/vnd.error

src/main/java/org/springframework/hateoas/VndErrors.java

@@ -0,0 +1,170 @@
+/*
+ * Copyright 2013 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.hateoas;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.List;
+
+import javax.xml.bind.annotation.XmlAttribute;
+import javax.xml.bind.annotation.XmlElement;
+import javax.xml.bind.annotation.XmlRootElement;
+import javax.xml.bind.annotation.XmlType;
+
+import org.springframework.util.Assert;
+
+import com.fasterxml.jackson.annotation.JsonValue;
+
+/**
+ * A representation model class to be rendered as specified for the media type {@code application/vnd.error}.
+ * 
+ * @see https://github.com/blongden/vnd.error
+ * @author Oliver Gierke
+ */
+@XmlRootElement(name = "errors")
+public class VndErrors implements Iterable<VndErrors.VndError> {
+
+	@XmlElement(name = "error")
+	private final List<VndError> vndErrors;
+
+	/**
+	 * Creates a new {@link VndErrors} instance containing a single {@link VndError} with the given logref, message and
+	 * optional {@link Link}s.
+	 * 
+	 * @param logref must not be {@literal null} or empty.
+	 * @param message must not be {@literal null} or empty.
+	 * @param links
+	 */
+	public VndErrors(String logref, String message, Link... links) {
+		this(new VndError(logref, message, links));
+	}
+
+	/**
+	 * Creates a new {@link VndErrors} wrapper for at least one {@link VndError}.
+	 * 
+	 * @param errors must not be {@literal null}.
+	 * @param errors
+	 */
+	public VndErrors(VndError error, VndError... errors) {
+
+		Assert.notNull(error, "Error must not be null");
+
+		this.vndErrors = new ArrayList<VndError>(errors.length + 1);
+		this.vndErrors.add(error);
+		this.vndErrors.addAll(Arrays.asList(errors));
+	}
+
+	/**
+	 * Protected default constructor to allow JAXB marshalling.
+	 */
+	protected VndErrors() {
+		this.vndErrors = new ArrayList<VndError>();
+	}
+
+	/**
+	 * Adds an additional {@link VndError} to the wrapper.
+	 * 
+	 * @param errors
+	 */
+	public VndErrors add(VndError error) {
+		this.vndErrors.add(error);
+		return this;
+	}
+
+	/**
+	 * Dummy method to allow {@link JsonValue} to be configured.
+	 * 
+	 * @return the vndErrors
+	 */
+	@com.fasterxml.jackson.annotation.JsonValue
+	@org.codehaus.jackson.annotate.JsonValue
+	private List<VndError> getErrors() {
+		return vndErrors;
+	}
+
+	/* 
+	 * (non-Javadoc)
+	 * @see java.lang.Iterable#iterator()
+	 */
+	@Override
+	public Iterator<VndErrors.VndError> iterator() {
+		return this.vndErrors.iterator();
+	}
+
+	/**
+	 * A single {@link VndError}.
+	 * 
+	 * @author Oliver Gierke
+	 */
+	@XmlType
+	public static class VndError extends ResourceSupport {
+
+		@com.fasterxml.jackson.annotation.JsonProperty
+		@org.codehaus.jackson.annotate.JsonProperty
+		@XmlAttribute
+		private final String logref;
+
+		@com.fasterxml.jackson.annotation.JsonProperty
+		@org.codehaus.jackson.annotate.JsonProperty
+		@XmlElement
+		private final String message;
+
+		/**
+		 * Creates a new {@link VndError} with the given logref, a message as well as some {@link Link}s.
+		 * 
+		 * @param logref must not be {@literal null} or empty.
+		 * @param message must not be {@literal null} or empty.
+		 * @param links
+		 */
+		public VndError(String logref, String message, Link... links) {
+
+			Assert.hasText(logref, "Logref must not be null or empty!");
+			Assert.hasText(message, "Message must not be null or empty!");
+
+			this.logref = logref;
+			this.message = message;
+			this.add(Arrays.asList(links));
+		}
+
+		/**
+		 * Protected default constructor to allow JAXB marshalling.
+		 */
+		protected VndError() {
+
+			this.logref = null;
+			this.message = null;
+		}
+
+		/**
+		 * Returns the logref of the error.
+		 * 
+		 * @return the logref
+		 */
+		public String getLogref() {
+			return logref;
+		}
+
+		/**
+		 * Returns the message of the error.
+		 * 
+		 * @return the message
+		 */
+		public String getMessage() {
+			return message;
+		}
+	}
+}