OZG-6240 KOP-2627 Add javadoc to getMessage

src/main/java/de/ozgcloud/xta/client/XtaClient.java

@@ -53,6 +53,13 @@ public class XtaClient {
 		return service.getStatusList(clientIdentifier, config.getMaxListItems());
 	}
 
+	/**
+	 * Fetch the message content, close the message, and then the fetch transport report
+	 * for the given {@code messageId} for the reader with identifier {@code clientIdentifier}.
+	 * @param clientIdentifier Identifier of the reading client
+	 * @param messageId Identifier of the message to fetch
+	 * @return The message and transport report
+	 */
 	public XtaMessageAndTransportReport getMessage(@NotBlank String clientIdentifier, @NotBlank String messageId)
 			throws XTAWSTechnicalProblemException, PermissionDeniedException, InvalidMessageIDException {
 		var identifier = deriveIdentifier(clientIdentifier);