feat: Add Microservice Pattern, Log aggregation (#2690) (#2719)

* feat: Add Microservice Pattern, Log aggregation.

Related: #2690

* docs: Add javaDoc for public methods.

Related: #2690

---------

Co-authored-by: Ilkka Seppälä <iluwatar@users.noreply.github.com>

log-aggregation/src/main/java/com/iluwatar/logaggregation/LogLevel.java

@@ -0,0 +1,38 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2023 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.logaggregation;
+
+/**
+ * Enum representing different log levels.
+ * Defines the severity of a log message, helping in filtering and prioritization.
+ * <ul>
+ *   <li>DEBUG: Detailed information, typically of interest only when diagnosing problems.</li>
+ *   <li>INFO: Confirmation that things are working as expected.</li>
+ *   <li>ERROR: Indicates a problem that needs attention.</li>
+ * </ul>
+ */
+public enum LogLevel {
+  DEBUG, INFO, ERROR
+}