Polishing cleanup and javadoc

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

@@ -202,6 +202,17 @@ public final class CloudEventMessageUtils {
 		return get(UUID.randomUUID().toString(), "1.0", ce_source, ce_type);
 	}
 
+	/**
+	 * Will attempt to convert 'inputMessage' to a binary-mode Cloud Event {@link Message}.
+	 * This typically happens when 'inputMessage' represents Cloud Event in structured-mode.
+	 * <br>
+	 * In the event the message already represents Cloud Event in binary-mode, or this
+	 * message does not represent Cloud Event at all, it will be returned unchanged.
+	 *
+	 * @param inputMessage instance of incoming {@link Message}
+	 * @param messageConverter instance of {@link MessageConverter} to assist with type conversion.
+	 * @return instance of {@link Message} representing Cloud Event in binary-mode or unchanged 'inputMessage'.
+	 */
 	@SuppressWarnings("unchecked")
 	public static Message<?> toBinary(Message<?> inputMessage, MessageConverter messageConverter) {
 
@@ -219,6 +230,7 @@ public final class CloudEventMessageUtils {
 						: MimeTypeUtils.APPLICATION_JSON_VALUE;
 
 				String suffix = contentType.getSubtypeSuffix();
+				Assert.hasText(suffix, "Content-type 'suffix' can not be determined from " + contentType);
 				MimeType cloudEventDeserializationContentType = MimeTypeUtils
 						.parseMimeType(contentType.getType() + "/" + suffix);
 				Message<?> cloudEventMessage = MessageBuilder.fromMessage(inputMessage)
@@ -238,6 +250,13 @@ public final class CloudEventMessageUtils {
 		return inputMessage;
 	}
 
+	/**
+	 * Will attempt to determine based on the headers the origin of Message (e.g., HTTP, Kafka etc)
+	 * and based on this designate prefix to be used for Cloud Events attributes (i.e., `ce-` or `ce_` etc).
+	 *
+	 * @param messageHeaders instance of {@link MessageHeaders}
+	 * @return prefix to be used for Cloud Events attributes
+	 */
 	public static String determinePrefixToUse(MessageHeaders messageHeaders) {
 		Set<String> keys = messageHeaders.keySet();
 		if (keys.contains("user-agent")) {

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/catalog/SimpleFunctionRegistry.java

@@ -47,6 +47,7 @@ import reactor.util.function.Tuples;
 
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.cloud.function.cloudevent.CloudEventAttributes;
 import org.springframework.cloud.function.cloudevent.CloudEventMessageUtils;
 import org.springframework.cloud.function.context.FunctionCatalog;
 import org.springframework.cloud.function.context.FunctionProperties;
@@ -910,13 +911,18 @@ public class SimpleFunctionRegistry implements FunctionRegistry, FunctionInspect
 		 * case that requires it since it may contain forwarding url
 		 */
 		private boolean containsRetainMessageSignalInHeaders(Message message) {
-			for (String headerName : message.getHeaders().keySet()) {
-				if (headerName.startsWith("lambda") ||
-					headerName.startsWith("scf-func-name")) {
-					return true;
-				}
+			if (new CloudEventAttributes(message.getHeaders()).isValidCloudEvent()) {
+				return true;
+			}
+			else {
+				for (String headerName : message.getHeaders().keySet()) {
+					if (headerName.startsWith("lambda") ||
+						headerName.startsWith("scf-func-name")) {
+						return true;
+					}
+				}
+				return false;
 			}
-			return false;
 		}
 
 		/*