GH-422 GH-606 Add support for normalizing structure-mode CE message

Normalizing in this context means converting it to binary-mode so the rest of the processing logic is the same.
Added support for canonical attribute names. Now, internally any attribute can be set as 'ce_' regardless where it came from are where it goes to as the frameork will be able to recognize both
Removed CloudEventMessageConverter
Renamed CloudEventAttributes to CloudEventAttributesHelperas it is better suited to what it actually does

Author: olegz

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/cloudevent/CloudEventAttributes.java

@@ -0,0 +1,125 @@
+/*
+ * Copyright 2019-2019 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
+ *
+ *      https://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.cloud.function.cloudevent;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.springframework.util.StringUtils;
+
+
+/**
+ *
+ * @author Oleg Zhurakousky
+ * @since 3.1
+ */
+public class CloudEventAttributesHelper extends HashMap<String, Object> {
+
+	/**
+	 *
+	 */
+	private static final long serialVersionUID = 5393610770855366497L;
+
+
+
+	CloudEventAttributesHelper(Map<String, Object> headers) {
+		super(headers);
+	}
+
+	@SuppressWarnings("unchecked")
+	public <A> A getId() {
+		if (this.containsKey(CloudEventMessageUtils.CANONICAL_ID)) {
+			return (A) this.get(CloudEventMessageUtils.CANONICAL_ID);
+		}
+		else if (this.containsKey(CloudEventMessageUtils.HTTP_ATTR_PREFIX + CloudEventMessageUtils.ID)) {
+			return (A) this.get(CloudEventMessageUtils.HTTP_ATTR_PREFIX + CloudEventMessageUtils.ID);
+		}
+		return null;
+	}
+
+	String getAttributeName(String attributeName) {
+		if (this.containsKey(CloudEventMessageUtils.ATTR_PREFIX + attributeName)) {
+			return CloudEventMessageUtils.ATTR_PREFIX + attributeName;
+		}
+		else if (this.containsKey(CloudEventMessageUtils.HTTP_ATTR_PREFIX + attributeName)) {
+			return CloudEventMessageUtils.HTTP_ATTR_PREFIX + attributeName;
+		}
+		return attributeName;
+	}
+
+	@SuppressWarnings("unchecked")
+	public <A> A getSource() {
+		if (this.containsKey(CloudEventMessageUtils.CANONICAL_SOURCE)) {
+			return (A) this.get(CloudEventMessageUtils.CANONICAL_SOURCE);
+		}
+		else if (this.containsKey(CloudEventMessageUtils.HTTP_ATTR_PREFIX + CloudEventMessageUtils.SOURCE)) {
+			return (A) this.get(CloudEventMessageUtils.HTTP_ATTR_PREFIX + CloudEventMessageUtils.SOURCE);
+		}
+		return (A) this.get(CloudEventMessageUtils.SOURCE);
+	}
+
+	@SuppressWarnings("unchecked")
+	public <A> A getSpecversion() {
+		if (this.containsKey(CloudEventMessageUtils.CANONICAL_SPECVERSION)) {
+			return (A) this.get(CloudEventMessageUtils.CANONICAL_SPECVERSION);
+		}
+		else if (this.containsKey(CloudEventMessageUtils.HTTP_ATTR_PREFIX + CloudEventMessageUtils.SPECVERSION)) {
+			return (A) this.get(CloudEventMessageUtils.HTTP_ATTR_PREFIX + CloudEventMessageUtils.SPECVERSION);
+		}
+		return (A) this.get(CloudEventMessageUtils.SPECVERSION);
+	}
+
+	@SuppressWarnings("unchecked")
+	public <A> A getType() {
+		if (this.containsKey(CloudEventMessageUtils.CANONICAL_TYPE)) {
+			return (A) this.get(CloudEventMessageUtils.CANONICAL_TYPE);
+		}
+		else if (this.containsKey(CloudEventMessageUtils.HTTP_ATTR_PREFIX + CloudEventMessageUtils.TYPE)) {
+			return (A) this.get(CloudEventMessageUtils.HTTP_ATTR_PREFIX + CloudEventMessageUtils.TYPE);
+		}
+		return (A) this.get(CloudEventMessageUtils.TYPE);
+	}
+
+	@SuppressWarnings("unchecked")
+	public <A> A getDataContentType() {
+		Object dataContentType;
+		if (this.containsKey(CloudEventMessageUtils.CANONICAL_DATACONTENTTYPE)) {
+			dataContentType = this.get(CloudEventMessageUtils.CANONICAL_DATACONTENTTYPE);
+		}
+		else if (this.containsKey(CloudEventMessageUtils.HTTP_ATTR_PREFIX + CloudEventMessageUtils.DATACONTENTTYPE)) {
+			dataContentType = this.get(CloudEventMessageUtils.HTTP_ATTR_PREFIX + CloudEventMessageUtils.DATACONTENTTYPE);
+		}
+		dataContentType = this.get(CloudEventMessageUtils.DATACONTENTTYPE);
+		return (A) dataContentType;
+	}
+
+	public void setDataContentType(String datacontenttype) {
+		this.put(CloudEventMessageUtils.CANONICAL_DATACONTENTTYPE, datacontenttype);
+	}
+
+	@SuppressWarnings("unchecked")
+	public <A> A getAtttribute(String name) {
+		return (A) this.get(name);
+	}
+
+	public boolean isValidCloudEvent() {
+		return StringUtils.hasText(this.getId())
+				&& StringUtils.hasText(this.getSource())
+				&& StringUtils.hasText(this.getSpecversion())
+				&& StringUtils.hasText(this.getType());
+	}
+}

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/cloudevent/CloudEventAttributesHelper.java

@@ -31,7 +31,7 @@ public interface CloudEventAttributesProvider {
 	 *
 	 * @param inputMessage input message used to invoke user functionality (e.g., function)
 	 * @param result result of the invocation of user functionality (e.g., function)
-	 * @return instance of {@link CloudEventAttributes}
+	 * @return instance of {@link CloudEventAttributesHelper}
 	 */
 	Map<String, Object> generateDefaultCloudEventHeaders(Message<?> inputMessage, Object result);
 }