diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..549e00a
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,33 @@
+HELP.md
+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/
diff --git a/.mvn/wrapper/maven-wrapper.jar b/.mvn/wrapper/maven-wrapper.jar
new file mode 100644
index 0000000..c1dd12f
Binary files /dev/null and b/.mvn/wrapper/maven-wrapper.jar differ
diff --git a/.mvn/wrapper/maven-wrapper.properties b/.mvn/wrapper/maven-wrapper.properties
new file mode 100644
index 0000000..b7cb93e
--- /dev/null
+++ b/.mvn/wrapper/maven-wrapper.properties
@@ -0,0 +1,2 @@
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.8.4/apache-maven-3.8.4-bin.zip
+wrapperUrl=https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar
diff --git a/mvnw b/mvnw
new file mode 100644
index 0000000..8a8fb22
--- /dev/null
+++ b/mvnw
@@ -0,0 +1,316 @@
+#!/bin/sh
+# ----------------------------------------------------------------------------
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+# ----------------------------------------------------------------------------
+
+# ----------------------------------------------------------------------------
+# Maven Start Up Batch script
+#
+# Required ENV vars:
+# ------------------
+#   JAVA_HOME - location of a JDK home dir
+#
+# Optional ENV vars
+# -----------------
+#   M2_HOME - location of maven2's installed home dir
+#   MAVEN_OPTS - parameters passed to the Java VM when running Maven
+#     e.g. to debug Maven itself, use
+#       set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+#   MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+# ----------------------------------------------------------------------------
+
+if [ -z "$MAVEN_SKIP_RC" ] ; then
+
+  if [ -f /usr/local/etc/mavenrc ] ; then
+    . /usr/local/etc/mavenrc
+  fi
+
+  if [ -f /etc/mavenrc ] ; then
+    . /etc/mavenrc
+  fi
+
+  if [ -f "$HOME/.mavenrc" ] ; then
+    . "$HOME/.mavenrc"
+  fi
+
+fi
+
+# OS specific support.  $var _must_ be set to either true or false.
+cygwin=false;
+darwin=false;
+mingw=false
+case "`uname`" in
+  CYGWIN*) cygwin=true ;;
+  MINGW*) mingw=true;;
+  Darwin*) darwin=true
+    # Use /usr/libexec/java_home if available, otherwise fall back to /Library/Java/Home
+    # See https://developer.apple.com/library/mac/qa/qa1170/_index.html
+    if [ -z "$JAVA_HOME" ]; then
+      if [ -x "/usr/libexec/java_home" ]; then
+        export JAVA_HOME="`/usr/libexec/java_home`"
+      else
+        export JAVA_HOME="/Library/Java/Home"
+      fi
+    fi
+    ;;
+esac
+
+if [ -z "$JAVA_HOME" ] ; then
+  if [ -r /etc/gentoo-release ] ; then
+    JAVA_HOME=`java-config --jre-home`
+  fi
+fi
+
+if [ -z "$M2_HOME" ] ; then
+  ## resolve links - $0 may be a link to maven's home
+  PRG="$0"
+
+  # need this for relative symlinks
+  while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+      PRG="$link"
+    else
+      PRG="`dirname "$PRG"`/$link"
+    fi
+  done
+
+  saveddir=`pwd`
+
+  M2_HOME=`dirname "$PRG"`/..
+
+  # make it fully qualified
+  M2_HOME=`cd "$M2_HOME" && pwd`
+
+  cd "$saveddir"
+  # echo Using m2 at $M2_HOME
+fi
+
+# For Cygwin, ensure paths are in UNIX format before anything is touched
+if $cygwin ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --unix "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --unix "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --unix "$CLASSPATH"`
+fi
+
+# For Mingw, ensure paths are in UNIX format before anything is touched
+if $mingw ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME="`(cd "$M2_HOME"; pwd)`"
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME="`(cd "$JAVA_HOME"; pwd)`"
+fi
+
+if [ -z "$JAVA_HOME" ]; then
+  javaExecutable="`which javac`"
+  if [ -n "$javaExecutable" ] && ! [ "`expr \"$javaExecutable\" : '\([^ ]*\)'`" = "no" ]; then
+    # readlink(1) is not available as standard on Solaris 10.
+    readLink=`which readlink`
+    if [ ! `expr "$readLink" : '\([^ ]*\)'` = "no" ]; then
+      if $darwin ; then
+        javaHome="`dirname \"$javaExecutable\"`"
+        javaExecutable="`cd \"$javaHome\" && pwd -P`/javac"
+      else
+        javaExecutable="`readlink -f \"$javaExecutable\"`"
+      fi
+      javaHome="`dirname \"$javaExecutable\"`"
+      javaHome=`expr "$javaHome" : '\(.*\)/bin'`
+      JAVA_HOME="$javaHome"
+      export JAVA_HOME
+    fi
+  fi
+fi
+
+if [ -z "$JAVACMD" ] ; then
+  if [ -n "$JAVA_HOME"  ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+      # IBM's JDK on AIX uses strange locations for the executables
+      JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+      JAVACMD="$JAVA_HOME/bin/java"
+    fi
+  else
+    JAVACMD="`\\unset -f command; \\command -v java`"
+  fi
+fi
+
+if [ ! -x "$JAVACMD" ] ; then
+  echo "Error: JAVA_HOME is not defined correctly." >&2
+  echo "  We cannot execute $JAVACMD" >&2
+  exit 1
+fi
+
+if [ -z "$JAVA_HOME" ] ; then
+  echo "Warning: JAVA_HOME environment variable is not set."
+fi
+
+CLASSWORLDS_LAUNCHER=org.codehaus.plexus.classworlds.launcher.Launcher
+
+# traverses directory structure from process work directory to filesystem root
+# first directory with .mvn subdirectory is considered project base directory
+find_maven_basedir() {
+
+  if [ -z "$1" ]
+  then
+    echo "Path not specified to find_maven_basedir"
+    return 1
+  fi
+
+  basedir="$1"
+  wdir="$1"
+  while [ "$wdir" != '/' ] ; do
+    if [ -d "$wdir"/.mvn ] ; then
+      basedir=$wdir
+      break
+    fi
+    # workaround for JBEAP-8937 (on Solaris 10/Sparc)
+    if [ -d "${wdir}" ]; then
+      wdir=`cd "$wdir/.."; pwd`
+    fi
+    # end of workaround
+  done
+  echo "${basedir}"
+}
+
+# concatenates all lines of a file
+concat_lines() {
+  if [ -f "$1" ]; then
+    echo "$(tr -s '\n' ' ' < "$1")"
+  fi
+}
+
+BASE_DIR=`find_maven_basedir "$(pwd)"`
+if [ -z "$BASE_DIR" ]; then
+  exit 1;
+fi
+
+##########################################################################################
+# Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+# This allows using the maven wrapper in projects that prohibit checking in binary data.
+##########################################################################################
+if [ -r "$BASE_DIR/.mvn/wrapper/maven-wrapper.jar" ]; then
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Found .mvn/wrapper/maven-wrapper.jar"
+    fi
+else
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Couldn't find .mvn/wrapper/maven-wrapper.jar, downloading it ..."
+    fi
+    if [ -n "$MVNW_REPOURL" ]; then
+      jarUrl="$MVNW_REPOURL/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar"
+    else
+      jarUrl="https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar"
+    fi
+    while IFS="=" read key value; do
+      case "$key" in (wrapperUrl) jarUrl="$value"; break ;;
+      esac
+    done < "$BASE_DIR/.mvn/wrapper/maven-wrapper.properties"
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Downloading from: $jarUrl"
+    fi
+    wrapperJarPath="$BASE_DIR/.mvn/wrapper/maven-wrapper.jar"
+    if $cygwin; then
+      wrapperJarPath=`cygpath --path --windows "$wrapperJarPath"`
+    fi
+
+    if command -v wget > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found wget ... using wget"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            wget "$jarUrl" -O "$wrapperJarPath" || rm -f "$wrapperJarPath"
+        else
+            wget --http-user=$MVNW_USERNAME --http-password=$MVNW_PASSWORD "$jarUrl" -O "$wrapperJarPath" || rm -f "$wrapperJarPath"
+        fi
+    elif command -v curl > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found curl ... using curl"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            curl -o "$wrapperJarPath" "$jarUrl" -f
+        else
+            curl --user $MVNW_USERNAME:$MVNW_PASSWORD -o "$wrapperJarPath" "$jarUrl" -f
+        fi
+
+    else
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Falling back to using Java to download"
+        fi
+        javaClass="$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.java"
+        # For Cygwin, switch paths to Windows format before running javac
+        if $cygwin; then
+          javaClass=`cygpath --path --windows "$javaClass"`
+        fi
+        if [ -e "$javaClass" ]; then
+            if [ ! -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Compiling MavenWrapperDownloader.java ..."
+                fi
+                # Compiling the Java class
+                ("$JAVA_HOME/bin/javac" "$javaClass")
+            fi
+            if [ -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                # Running the downloader
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Running MavenWrapperDownloader.java ..."
+                fi
+                ("$JAVA_HOME/bin/java" -cp .mvn/wrapper MavenWrapperDownloader "$MAVEN_PROJECTBASEDIR")
+            fi
+        fi
+    fi
+fi
+##########################################################################################
+# End of extension
+##########################################################################################
+
+export MAVEN_PROJECTBASEDIR=${MAVEN_BASEDIR:-"$BASE_DIR"}
+if [ "$MVNW_VERBOSE" = true ]; then
+  echo $MAVEN_PROJECTBASEDIR
+fi
+MAVEN_OPTS="$(concat_lines "$MAVEN_PROJECTBASEDIR/.mvn/jvm.config") $MAVEN_OPTS"
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --path --windows "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --path --windows "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --windows "$CLASSPATH"`
+  [ -n "$MAVEN_PROJECTBASEDIR" ] &&
+    MAVEN_PROJECTBASEDIR=`cygpath --path --windows "$MAVEN_PROJECTBASEDIR"`
+fi
+
+# Provide a "standardized" way to retrieve the CLI args that will
+# work with both Windows and non-Windows executions.
+MAVEN_CMD_LINE_ARGS="$MAVEN_CONFIG $@"
+export MAVEN_CMD_LINE_ARGS
+
+WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+exec "$JAVACMD" \
+  $MAVEN_OPTS \
+  $MAVEN_DEBUG_OPTS \
+  -classpath "$MAVEN_PROJECTBASEDIR/.mvn/wrapper/maven-wrapper.jar" \
+  "-Dmaven.home=${M2_HOME}" \
+  "-Dmaven.multiModuleProjectDirectory=${MAVEN_PROJECTBASEDIR}" \
+  ${WRAPPER_LAUNCHER} $MAVEN_CONFIG "$@"
diff --git a/mvnw.cmd b/mvnw.cmd
new file mode 100644
index 0000000..1d8ab01
--- /dev/null
+++ b/mvnw.cmd
@@ -0,0 +1,188 @@
+@REM ----------------------------------------------------------------------------
+@REM Licensed to the Apache Software Foundation (ASF) under one
+@REM or more contributor license agreements.  See the NOTICE file
+@REM distributed with this work for additional information
+@REM regarding copyright ownership.  The ASF licenses this file
+@REM to you under the Apache License, Version 2.0 (the
+@REM "License"); you may not use this file except in compliance
+@REM with the License.  You may obtain a copy of the License at
+@REM
+@REM    https://www.apache.org/licenses/LICENSE-2.0
+@REM
+@REM Unless required by applicable law or agreed to in writing,
+@REM software distributed under the License is distributed on an
+@REM "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+@REM KIND, either express or implied.  See the License for the
+@REM specific language governing permissions and limitations
+@REM under the License.
+@REM ----------------------------------------------------------------------------
+
+@REM ----------------------------------------------------------------------------
+@REM Maven Start Up Batch script
+@REM
+@REM Required ENV vars:
+@REM JAVA_HOME - location of a JDK home dir
+@REM
+@REM Optional ENV vars
+@REM M2_HOME - location of maven2's installed home dir
+@REM MAVEN_BATCH_ECHO - set to 'on' to enable the echoing of the batch commands
+@REM MAVEN_BATCH_PAUSE - set to 'on' to wait for a keystroke before ending
+@REM MAVEN_OPTS - parameters passed to the Java VM when running Maven
+@REM     e.g. to debug Maven itself, use
+@REM set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+@REM MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+@REM ----------------------------------------------------------------------------
+
+@REM Begin all REM lines with '@' in case MAVEN_BATCH_ECHO is 'on'
+@echo off
+@REM set title of command window
+title %0
+@REM enable echoing by setting MAVEN_BATCH_ECHO to 'on'
+@if "%MAVEN_BATCH_ECHO%" == "on"  echo %MAVEN_BATCH_ECHO%
+
+@REM set %HOME% to equivalent of $HOME
+if "%HOME%" == "" (set "HOME=%HOMEDRIVE%%HOMEPATH%")
+
+@REM Execute a user defined script before this one
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPre
+@REM check for pre script, once with legacy .bat ending and once with .cmd ending
+if exist "%USERPROFILE%\mavenrc_pre.bat" call "%USERPROFILE%\mavenrc_pre.bat" %*
+if exist "%USERPROFILE%\mavenrc_pre.cmd" call "%USERPROFILE%\mavenrc_pre.cmd" %*
+:skipRcPre
+
+@setlocal
+
+set ERROR_CODE=0
+
+@REM To isolate internal variables from possible post scripts, we use another setlocal
+@setlocal
+
+@REM ==== START VALIDATION ====
+if not "%JAVA_HOME%" == "" goto OkJHome
+
+echo.
+echo Error: JAVA_HOME not found in your environment. >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+:OkJHome
+if exist "%JAVA_HOME%\bin\java.exe" goto init
+
+echo.
+echo Error: JAVA_HOME is set to an invalid directory. >&2
+echo JAVA_HOME = "%JAVA_HOME%" >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+@REM ==== END VALIDATION ====
+
+:init
+
+@REM Find the project base dir, i.e. the directory that contains the folder ".mvn".
+@REM Fallback to current working directory if not found.
+
+set MAVEN_PROJECTBASEDIR=%MAVEN_BASEDIR%
+IF NOT "%MAVEN_PROJECTBASEDIR%"=="" goto endDetectBaseDir
+
+set EXEC_DIR=%CD%
+set WDIR=%EXEC_DIR%
+:findBaseDir
+IF EXIST "%WDIR%"\.mvn goto baseDirFound
+cd ..
+IF "%WDIR%"=="%CD%" goto baseDirNotFound
+set WDIR=%CD%
+goto findBaseDir
+
+:baseDirFound
+set MAVEN_PROJECTBASEDIR=%WDIR%
+cd "%EXEC_DIR%"
+goto endDetectBaseDir
+
+:baseDirNotFound
+set MAVEN_PROJECTBASEDIR=%EXEC_DIR%
+cd "%EXEC_DIR%"
+
+:endDetectBaseDir
+
+IF NOT EXIST "%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config" goto endReadAdditionalConfig
+
+@setlocal EnableExtensions EnableDelayedExpansion
+for /F "usebackq delims=" %%a in ("%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config") do set JVM_CONFIG_MAVEN_PROPS=!JVM_CONFIG_MAVEN_PROPS! %%a
+@endlocal & set JVM_CONFIG_MAVEN_PROPS=%JVM_CONFIG_MAVEN_PROPS%
+
+:endReadAdditionalConfig
+
+SET MAVEN_JAVA_EXE="%JAVA_HOME%\bin\java.exe"
+set WRAPPER_JAR="%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.jar"
+set WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+set DOWNLOAD_URL="https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar"
+
+FOR /F "usebackq tokens=1,2 delims==" %%A IN ("%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.properties") DO (
+    IF "%%A"=="wrapperUrl" SET DOWNLOAD_URL=%%B
+)
+
+@REM Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+@REM This allows using the maven wrapper in projects that prohibit checking in binary data.
+if exist %WRAPPER_JAR% (
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Found %WRAPPER_JAR%
+    )
+) else (
+    if not "%MVNW_REPOURL%" == "" (
+        SET DOWNLOAD_URL="%MVNW_REPOURL%/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar"
+    )
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Couldn't find %WRAPPER_JAR%, downloading it ...
+        echo Downloading from: %DOWNLOAD_URL%
+    )
+
+    powershell -Command "&{"^
+		"$webclient = new-object System.Net.WebClient;"^
+		"if (-not ([string]::IsNullOrEmpty('%MVNW_USERNAME%') -and [string]::IsNullOrEmpty('%MVNW_PASSWORD%'))) {"^
+		"$webclient.Credentials = new-object System.Net.NetworkCredential('%MVNW_USERNAME%', '%MVNW_PASSWORD%');"^
+		"}"^
+		"[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; $webclient.DownloadFile('%DOWNLOAD_URL%', '%WRAPPER_JAR%')"^
+		"}"
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Finished downloading %WRAPPER_JAR%
+    )
+)
+@REM End of extension
+
+@REM Provide a "standardized" way to retrieve the CLI args that will
+@REM work with both Windows and non-Windows executions.
+set MAVEN_CMD_LINE_ARGS=%*
+
+%MAVEN_JAVA_EXE% ^
+  %JVM_CONFIG_MAVEN_PROPS% ^
+  %MAVEN_OPTS% ^
+  %MAVEN_DEBUG_OPTS% ^
+  -classpath %WRAPPER_JAR% ^
+  "-Dmaven.multiModuleProjectDirectory=%MAVEN_PROJECTBASEDIR%" ^
+  %WRAPPER_LAUNCHER% %MAVEN_CONFIG% %*
+if ERRORLEVEL 1 goto error
+goto end
+
+:error
+set ERROR_CODE=1
+
+:end
+@endlocal & set ERROR_CODE=%ERROR_CODE%
+
+if not "%MAVEN_SKIP_RC%"=="" goto skipRcPost
+@REM check for post script, once with legacy .bat ending and once with .cmd ending
+if exist "%USERPROFILE%\mavenrc_post.bat" call "%USERPROFILE%\mavenrc_post.bat"
+if exist "%USERPROFILE%\mavenrc_post.cmd" call "%USERPROFILE%\mavenrc_post.cmd"
+:skipRcPost
+
+@REM pause the script if MAVEN_BATCH_PAUSE is set to 'on'
+if "%MAVEN_BATCH_PAUSE%"=="on" pause
+
+if "%MAVEN_TERMINATE_CMD%"=="on" exit %ERROR_CODE%
+
+cmd /C exit /B %ERROR_CODE%
diff --git a/pom.xml b/pom.xml
new file mode 100644
index 0000000..0af46cc
--- /dev/null
+++ b/pom.xml
@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>2.6.3</version>
+        <relativePath/> <!-- lookup parent from repository -->
+    </parent>
+    <groupId>com.gdn.onboarding</groupId>
+    <artifactId>onboarding-java</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>Onboarding Java</name>
+    <description>Onboarding Java</description>
+    <properties>
+        <java.version>1.8</java.version>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>
diff --git a/src/main/java/com/gdn/onboarding/onboardingjava/Calendar.java b/src/main/java/com/gdn/onboarding/onboardingjava/Calendar.java
new file mode 100644
index 0000000..1380b3d
--- /dev/null
+++ b/src/main/java/com/gdn/onboarding/onboardingjava/Calendar.java
@@ -0,0 +1,21 @@
+package com.gdn.onboarding.onboardingjava;
+
+public class Calendar {
+    public String getMonth(Integer n) throws Exception {
+        switch (n) {
+            case 1 : return "January";
+            case 2 : return "February";
+            case 3 : return "March";
+            case 4 : return "April";
+            case 5 : return "May";
+            case 6 : return "June";
+            case 7 : return "July";
+            case 8 : return "August";
+            case 9 : return "September";
+            case 10 : return "October";
+            case 11 : return "November";
+            case 12 : return "December";
+            default : throw new Exception();
+        }
+    }
+}
diff --git a/src/main/java/com/gdn/onboarding/onboardingjava/Factorial.java b/src/main/java/com/gdn/onboarding/onboardingjava/Factorial.java
new file mode 100644
index 0000000..4ff2081
--- /dev/null
+++ b/src/main/java/com/gdn/onboarding/onboardingjava/Factorial.java
@@ -0,0 +1,15 @@
+package com.gdn.onboarding.onboardingjava;
+
+public class Factorial {
+    private Integer sum = 1;
+    public Integer fact(Integer n) throws Exception {
+        if (n < 0) {
+            throw new Exception();
+        } else {
+            for (Integer i = 1; i <= n; i++) {
+                sum *= i;
+            }
+            return sum;
+        }
+    }
+}
diff --git a/src/main/java/com/gdn/onboarding/onboardingjava/LetterGrade.java b/src/main/java/com/gdn/onboarding/onboardingjava/LetterGrade.java
new file mode 100644
index 0000000..473b613
--- /dev/null
+++ b/src/main/java/com/gdn/onboarding/onboardingjava/LetterGrade.java
@@ -0,0 +1,26 @@
+package com.gdn.onboarding.onboardingjava;
+
+public class LetterGrade {
+    /*
+    A = 81 - 100
+    B = 61 - 80
+    C = 41 - 60
+    D = 21 - 40
+    E = 0 - 20
+     */
+    public String convertToLetter(Integer score) throws Exception {
+        if (score > 80 && score <= 100) {
+            return "A";
+        } else if (score > 60) {
+            return "B";
+        } else if (score > 40) {
+            return "C";
+        } else if (score > 20) {
+            return "D";
+        } else if (score > 0){
+            return "E";
+        } else {
+            throw new Exception();
+        }
+    }
+}
diff --git a/src/main/java/com/gdn/onboarding/onboardingjava/OnboardingJavaApplication.java b/src/main/java/com/gdn/onboarding/onboardingjava/OnboardingJavaApplication.java
new file mode 100644
index 0000000..1fe2f2d
--- /dev/null
+++ b/src/main/java/com/gdn/onboarding/onboardingjava/OnboardingJavaApplication.java
@@ -0,0 +1,13 @@
+package com.gdn.onboarding.onboardingjava;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class OnboardingJavaApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(OnboardingJavaApplication.class, args);
+    }
+
+}
diff --git a/src/main/java/com/gdn/onboarding/onboardingjava/ToDoList.java b/src/main/java/com/gdn/onboarding/onboardingjava/ToDoList.java
new file mode 100644
index 0000000..57e74e6
--- /dev/null
+++ b/src/main/java/com/gdn/onboarding/onboardingjava/ToDoList.java
@@ -0,0 +1,123 @@
+package com.gdn.onboarding.onboardingjava;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Scanner;
+
+public class ToDoList {
+    private static List<Todo> td = new ArrayList<>();
+
+    public static class Todo {
+        String content;
+
+        public Todo(String content) {
+            this.content = content;
+        }
+
+        public String getContent() {
+            return content;
+        }
+        public void setContent(String content) {
+            this.content = content;
+        }
+    }
+
+    public static void mainMenu() {
+        Scanner scan = new Scanner(System.in);
+        System.out.println("Main Menu");
+        System.out.println("1.Add to todos");
+        System.out.println("2.View todos");
+        System.out.println("3.Update a todo");
+        System.out.println("4.Delete a todo");
+        System.out.println("5.Exit");
+        System.out.print("Choice : ");
+        Integer in = scan.nextInt();
+        while (in < 1 || in > 5) {
+            System.out.println("invalid!");
+            System.out.print("Choice : ");
+            in = scan.nextInt();
+        }
+        if (in == 1) {
+            addTodo();
+        } else if (in == 2) {
+            viewTodo();
+        } else if (in == 3) {
+            updateTodo();
+        } else if (in == 4){
+            deleteTodo();
+        } else {
+            return;
+        }
+    }
+
+    public static void deleteTodo() {
+        Scanner scan = new Scanner(System.in);
+        if (td.isEmpty()) {
+            System.out.println("Your Todos are empty!\n");
+        } else {
+            System.out.println("Which id? : ");
+            Integer idx = scan.nextInt();
+            while (idx > td.size() || idx < 0) {
+                System.out.println("Invalid input");
+                System.out.println("Which id? : ");
+                String temp = scan.nextLine();
+                idx = scan.nextInt();
+            }
+            td.remove(idx-1);
+            System.out.println("Deleted\n");
+        }
+        mainMenu();
+    }
+
+    public static void updateTodo() {
+        Scanner scan = new Scanner(System.in);
+        if (td.isEmpty()) {
+            System.out.println("Your Todos are empty!\n");
+        } else {
+            System.out.println("Which id? : ");
+            Integer idx = scan.nextInt();
+            while (idx > td.size() || idx < 0) {
+                System.out.println("Invalid input");
+                System.out.println("Which id? : ");
+                idx = scan.nextInt();
+            }
+            String temp = scan.nextLine();
+            System.out.println("Change to what? : ");
+            String newContent = scan.nextLine();
+            Todo newTodo = new Todo(newContent);
+            td.set(idx-1, newTodo);
+            System.out.println("Updated\n");
+        }
+        mainMenu();
+    }
+
+    public static void viewTodo() {
+        Scanner scan = new Scanner(System.in);
+        if (td.isEmpty()) {
+            System.out.println("Your Todos are empty!\n");
+        } else {
+            Integer num = 1;
+            for (Todo todo : td) {
+                System.out.println("id: " + num + ", content: " + todo.getContent());
+                num++;
+            }
+            System.out.println("You've reached the bottom!\n");
+        }
+        mainMenu();
+    }
+
+    public static void addTodo() {
+        Scanner scan = new Scanner(System.in);
+        System.out.print("Insert new todo : ");
+        String content = scan.nextLine();
+        Todo todo = new Todo(content);
+        td.add(todo);
+        System.out.println("Added!\n");
+        mainMenu();
+    }
+
+
+    public static void main(String[] args) {
+        mainMenu();
+    }
+}
diff --git a/src/main/resources/application.properties b/src/main/resources/application.properties
new file mode 100644
index 0000000..e429494
--- /dev/null
+++ b/src/main/resources/application.properties
@@ -0,0 +1 @@
+logging.level.root = trace
diff --git a/src/test/java/com/gdn/onboarding/onboardingjava/CalendarTest.java b/src/test/java/com/gdn/onboarding/onboardingjava/CalendarTest.java
new file mode 100644
index 0000000..6d8aceb
--- /dev/null
+++ b/src/test/java/com/gdn/onboarding/onboardingjava/CalendarTest.java
@@ -0,0 +1,15 @@
+package com.gdn.onboarding.onboardingjava;
+
+import org.junit.jupiter.api.Test;
+
+public class CalendarTest {
+    @Test
+    public void testGetMonth_success() throws Exception{
+        String tc = new Calendar().getMonth(10);
+        if (!tc.equals("October")) {
+            System.out.println("GAGAL");
+            throw new Exception();
+        }
+    }
+
+}
diff --git a/src/test/java/com/gdn/onboarding/onboardingjava/FactorialTest.java b/src/test/java/com/gdn/onboarding/onboardingjava/FactorialTest.java
new file mode 100644
index 0000000..663bd27
--- /dev/null
+++ b/src/test/java/com/gdn/onboarding/onboardingjava/FactorialTest.java
@@ -0,0 +1,14 @@
+package com.gdn.onboarding.onboardingjava;
+
+import org.junit.jupiter.api.Test;
+
+public class FactorialTest {
+    @Test
+    public void testFact_success() throws Exception{
+        Integer tc = new Factorial().fact(4);
+        if (tc != 24) {
+            System.out.println("GAGAL");
+            throw new Exception();
+        }
+    }
+}
diff --git a/src/test/java/com/gdn/onboarding/onboardingjava/LetterGradeTest.java b/src/test/java/com/gdn/onboarding/onboardingjava/LetterGradeTest.java
new file mode 100644
index 0000000..b1f084b
--- /dev/null
+++ b/src/test/java/com/gdn/onboarding/onboardingjava/LetterGradeTest.java
@@ -0,0 +1,14 @@
+package com.gdn.onboarding.onboardingjava;
+
+import org.junit.jupiter.api.Test;
+
+public class LetterGradeTest {
+    @Test
+    public void testConvertToLetter_success() throws Exception {
+        String tc = new LetterGrade().convertToLetter(75);
+        if (!tc.equals("B")) {
+            System.out.println("GAGAL");
+            throw new Exception();
+        }
+    }
+}
diff --git a/src/test/java/com/gdn/onboarding/onboardingjava/OnboardingJavaApplicationTests.java b/src/test/java/com/gdn/onboarding/onboardingjava/OnboardingJavaApplicationTests.java
new file mode 100644
index 0000000..b2ebf98
--- /dev/null
+++ b/src/test/java/com/gdn/onboarding/onboardingjava/OnboardingJavaApplicationTests.java
@@ -0,0 +1,13 @@
+package com.gdn.onboarding.onboardingjava;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest
+class OnboardingJavaApplicationTests {
+
+    @Test
+    void contextLoads() {
+    }
+
+}