Java Guild course · The Rebuild · Phase 1

Phase 1 · commits 1–5

Baseline and build hygiene

Nothing here changes a line of behaviour. It makes the project honest about what it is, and reproducible for whoever opens it next.

How to use this page

Every commit below is a numbered list of edits, then a verification, then the commit. mvn means ~/.local/maven/bin/mvn with JAVA_HOME set — see the setup block. Where a step says find this / replace with this, the “find” block is the code exactly as it stands after the previous commit.

1 · add the starter project exactly as supplied

chore · 8b314f7

Why

Baseline commit of the unmodified Solirius starter, so that every change that follows is visible as a diff against what was handed over.

Step 1. Unpack the supplied starter into a working directory and change into it. Do not edit anything yet:

unzip java-guild-candidate-test-intermediate-main.zip
cd java-guild-candidate-test-intermediate-main

Step 2. Put it under version control as it arrived. This is the only commit that contains code you did not write, which is exactly why it is on its own — every later diff is measured against it:

git init -b main
git config user.name  "Tom Spencer"
git config user.email "tomspencerlondon@gmail.com"

Step 3. Check it compiles before you trust it:

mvn clean test
# BUILD SUCCESS - and note: "No tests to run"

Step 4. Commit:

git add -A
git commit -F- <<'EOF'
chore: add the starter project exactly as supplied

Baseline commit of the unmodified Solirius starter, so that every
change that follows is visible as a diff against what was handed over.
EOF

2 · replace the placeholder groupId

build · d910e09

Why

The starter shipped groupId as the literal string "groupId". Set it to the project's real coordinates so the artefact is identifiable.

Step 1. In pom.xml, find:

<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>groupId</groupId>
    <artifactId>java-guild-candidate-test</artifactId>
    <version>1.0-SNAPSHOT</version>
    <properties>
        <maven.compiler.source>11</maven.compiler.source>

and replace it with:

<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.solirius.intermediate</groupId>
    <artifactId>java-guild-candidate-test</artifactId>
    <version>1.0-SNAPSHOT</version>
    <properties>
        <maven.compiler.source>11</maven.compiler.source>

Step 2. Verify:

mvn clean test
# BUILD SUCCESS - no tests yet

Step 3. Commit:

git add -A
git commit -F- <<'EOF'
build: replace the placeholder groupId

The starter shipped groupId as the literal string "groupId". Set it to
the project's real coordinates so the artefact is identifiable.
EOF

3 · compile with --release 11

build · 6a1aa9a

Why

source/target only set the language level and bytecode version; the code is still compiled against the running JDK's API, so a call added by a later JDK compiles here and fails at run time on 11.

Step 1. In pom.xml, find:

    <groupId>com.solirius.intermediate</groupId>
    <artifactId>java-guild-candidate-test</artifactId>
    <version>1.0-SNAPSHOT</version>
    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    </properties>
    <dependencies>

and replace it with:

    <groupId>com.solirius.intermediate</groupId>
    <artifactId>java-guild-candidate-test</artifactId>
    <version>1.0-SNAPSHOT</version>
    <properties>
        <maven.compiler.release>11</maven.compiler.release>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    </properties>
    <dependencies>

Step 2. Verify:

mvn clean test
# BUILD SUCCESS - no tests yet

Step 3. Commit:

git add -A
git commit -F- <<'EOF'
build: compile with --release 11

source/target only set the language level and bytecode version; the code
is still compiled against the running JDK's API, so a call added by a
later JDK compiles here and fails at run time on 11.

--release also compiles against the Java 11 API itself. On a modern JDK
it silences:

  location of system modules is not set in conjunction with -source 11

The target version is unchanged, so no record types, sealed types or
switch expressions appear anywhere in the submission.
EOF

4 · add a Maven wrapper pinned to 3.9.16

build · c7de5f2

Why

A reviewer can now build with ./mvnw and get the same Maven version the project was developed against, without installing one.

Step 1. Create .mvn/wrapper/maven-wrapper.properties:

wrapperVersion=3.3.4
distributionType=only-script
distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.16/apache-maven-3.9.16-bin.zip

Step 2. Create mvnw:

#!/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
#
#    http://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.
# ----------------------------------------------------------------------------

# ----------------------------------------------------------------------------
# Apache Maven Wrapper startup batch script, version 3.3.4
#
# Optional ENV vars
# -----------------
#   JAVA_HOME - location of a JDK home dir, required when download maven via java source
#   MVNW_REPOURL - repo url base for downloading maven distribution
#   MVNW_USERNAME/MVNW_PASSWORD - user and password for downloading maven
#   MVNW_VERBOSE - true: enable verbose log; debug: trace the mvnw script; others: silence the output
# ----------------------------------------------------------------------------

set -euf
[ "${MVNW_VERBOSE-}" != debug ] || set -x

# OS specific support.
native_path() { printf %s\\n "$1"; }
case "$(uname)" in
CYGWIN* | MINGW*)
  [ -z "${JAVA_HOME-}" ] || JAVA_HOME="$(cygpath --unix "$JAVA_HOME")"
  native_path() { cygpath --path --windows "$1"; }
  ;;
esac

# set JAVACMD and JAVACCMD
set_java_home() {
  # For Cygwin and MinGW, ensure paths are in Unix format before anything is touched
  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="$JAVA_HOME/jre/sh/java"
      JAVACCMD="$JAVA_HOME/jre/sh/javac"
    else
      JAVACMD="$JAVA_HOME/bin/java"
      JAVACCMD="$JAVA_HOME/bin/javac"

      if [ ! -x "$JAVACMD" ] || [ ! -x "$JAVACCMD" ]; then
        echo "The JAVA_HOME environment variable is not defined correctly, so mvnw cannot run." >&2
        echo "JAVA_HOME is set to \"$JAVA_HOME\", but \"\$JAVA_HOME/bin/java\" or \"\$JAVA_HOME/bin/javac\" does not exist." >&2
        return 1
      fi
    fi
  else
    JAVACMD="$(
      'set' +e
      'unset' -f command 2>/dev/null
      'command' -v java
    )" || :
    JAVACCMD="$(
      'set' +e
      'unset' -f command 2>/dev/null
      'command' -v javac
    )" || :

    if [ ! -x "${JAVACMD-}" ] || [ ! -x "${JAVACCMD-}" ]; then
      echo "The java/javac command does not exist in PATH nor is JAVA_HOME set, so mvnw cannot run." >&2
      return 1
    fi
  fi
}

# hash string like Java String::hashCode
hash_string() {
  str="${1:-}" h=0
  while [ -n "$str" ]; do
    char="${str%"${str#?}"}"
    h=$(((h * 31 + $(LC_CTYPE=C printf %d "'$char")) % 4294967296))
    str="${str#?}"
  done
  printf %x\\n $h
}

verbose() { :; }
[ "${MVNW_VERBOSE-}" != true ] || verbose() { printf %s\\n "${1-}"; }

die() {
  printf %s\\n "$1" >&2
  exit 1
}

trim() {
  # MWRAPPER-139:
  #   Trims trailing and leading whitespace, carriage returns, tabs, and linefeeds.
  #   Needed for removing poorly interpreted newline sequences when running in more
  #   exotic environments such as mingw bash on Windows.
  printf "%s" "${1}" | tr -d '[:space:]'
}

scriptDir="$(dirname "$0")"
scriptName="$(basename "$0")"

# parse distributionUrl and optional distributionSha256Sum, requires .mvn/wrapper/maven-wrapper.properties
while IFS="=" read -r key value; do
  case "${key-}" in
  distributionUrl) distributionUrl=$(trim "${value-}") ;;
  distributionSha256Sum) distributionSha256Sum=$(trim "${value-}") ;;
  esac
done <"$scriptDir/.mvn/wrapper/maven-wrapper.properties"
[ -n "${distributionUrl-}" ] || die "cannot read distributionUrl property in $scriptDir/.mvn/wrapper/maven-wrapper.properties"

case "${distributionUrl##*/}" in
maven-mvnd-*bin.*)
  MVN_CMD=mvnd.sh _MVNW_REPO_PATTERN=/maven/mvnd/
  case "${PROCESSOR_ARCHITECTURE-}${PROCESSOR_ARCHITEW6432-}:$(uname -a)" in
  *AMD64:CYGWIN* | *AMD64:MINGW*) distributionPlatform=windows-amd64 ;;
  :Darwin*x86_64) distributionPlatform=darwin-amd64 ;;
  :Darwin*arm64) distributionPlatform=darwin-aarch64 ;;
  :Linux*x86_64*) distributionPlatform=linux-amd64 ;;
  *)
    echo "Cannot detect native platform for mvnd on $(uname)-$(uname -m), use pure java version" >&2
    distributionPlatform=linux-amd64
    ;;
  esac
  distributionUrl="${distributionUrl%-bin.*}-$distributionPlatform.zip"
  ;;
maven-mvnd-*) MVN_CMD=mvnd.sh _MVNW_REPO_PATTERN=/maven/mvnd/ ;;
*) MVN_CMD="mvn${scriptName#mvnw}" _MVNW_REPO_PATTERN=/org/apache/maven/ ;;
esac

# apply MVNW_REPOURL and calculate MAVEN_HOME
# maven home pattern: ~/.m2/wrapper/dists/{apache-maven-<version>,maven-mvnd-<version>-<platform>}/<hash>
[ -z "${MVNW_REPOURL-}" ] || distributionUrl="$MVNW_REPOURL$_MVNW_REPO_PATTERN${distributionUrl#*"$_MVNW_REPO_PATTERN"}"
distributionUrlName="${distributionUrl##*/}"
distributionUrlNameMain="${distributionUrlName%.*}"
distributionUrlNameMain="${distributionUrlNameMain%-bin}"
MAVEN_USER_HOME="${MAVEN_USER_HOME:-${HOME}/.m2}"
MAVEN_HOME="${MAVEN_USER_HOME}/wrapper/dists/${distributionUrlNameMain-}/$(hash_string "$distributionUrl")"

exec_maven() {
  unset MVNW_VERBOSE MVNW_USERNAME MVNW_PASSWORD MVNW_REPOURL || :
  exec "$MAVEN_HOME/bin/$MVN_CMD" "$@" || die "cannot exec $MAVEN_HOME/bin/$MVN_CMD"
}

if [ -d "$MAVEN_HOME" ]; then
  verbose "found existing MAVEN_HOME at $MAVEN_HOME"
  exec_maven "$@"
fi

case "${distributionUrl-}" in
*?-bin.zip | *?maven-mvnd-?*-?*.zip) ;;
*) die "distributionUrl is not valid, must match *-bin.zip or maven-mvnd-*.zip, but found '${distributionUrl-}'" ;;
esac

# prepare tmp dir
if TMP_DOWNLOAD_DIR="$(mktemp -d)" && [ -d "$TMP_DOWNLOAD_DIR" ]; then
  clean() { rm -rf -- "$TMP_DOWNLOAD_DIR"; }
  trap clean HUP INT TERM EXIT
else
  die "cannot create temp dir"
fi

mkdir -p -- "${MAVEN_HOME%/*}"

# Download and Install Apache Maven
verbose "Couldn't find MAVEN_HOME, downloading and installing it ..."
verbose "Downloading from: $distributionUrl"
verbose "Downloading to: $TMP_DOWNLOAD_DIR/$distributionUrlName"

# select .zip or .tar.gz
if ! command -v unzip >/dev/null; then
  distributionUrl="${distributionUrl%.zip}.tar.gz"
  distributionUrlName="${distributionUrl##*/}"
fi

# verbose opt
__MVNW_QUIET_WGET=--quiet __MVNW_QUIET_CURL=--silent __MVNW_QUIET_UNZIP=-q __MVNW_QUIET_TAR=''
[ "${MVNW_VERBOSE-}" != true ] || __MVNW_QUIET_WGET='' __MVNW_QUIET_CURL='' __MVNW_QUIET_UNZIP='' __MVNW_QUIET_TAR=v

# normalize http auth
case "${MVNW_PASSWORD:+has-password}" in
'') MVNW_USERNAME='' MVNW_PASSWORD='' ;;
has-password) [ -n "${MVNW_USERNAME-}" ] || MVNW_USERNAME='' MVNW_PASSWORD='' ;;
esac

if [ -z "${MVNW_USERNAME-}" ] && command -v wget >/dev/null; then
  verbose "Found wget ... using wget"
  wget ${__MVNW_QUIET_WGET:+"$__MVNW_QUIET_WGET"} "$distributionUrl" -O "$TMP_DOWNLOAD_DIR/$distributionUrlName" || die "wget: Failed to fetch $distributionUrl"
elif [ -z "${MVNW_USERNAME-}" ] && command -v curl >/dev/null; then
  verbose "Found curl ... using curl"
  curl ${__MVNW_QUIET_CURL:+"$__MVNW_QUIET_CURL"} -f -L -o "$TMP_DOWNLOAD_DIR/$distributionUrlName" "$distributionUrl" || die "curl: Failed to fetch $distributionUrl"
elif set_java_home; then
  verbose "Falling back to use Java to download"
  javaSource="$TMP_DOWNLOAD_DIR/Downloader.java"
  targetZip="$TMP_DOWNLOAD_DIR/$distributionUrlName"
  cat >"$javaSource" <<-END
	public class Downloader extends java.net.Authenticator
	{
	  protected java.net.PasswordAuthentication getPasswordAuthentication()
	  {
	    return new java.net.PasswordAuthentication( System.getenv( "MVNW_USERNAME" ), System.getenv( "MVNW_PASSWORD" ).toCharArray() );
	  }
	  public static void main( String[] args ) throws Exception
	  {
	    setDefault( new Downloader() );
	    java.nio.file.Files.copy( java.net.URI.create( args[0] ).toURL().openStream(), java.nio.file.Paths.get( args[1] ).toAbsolutePath().normalize() );
	  }
	}
	END
  # For Cygwin/MinGW, switch paths to Windows format before running javac and java
  verbose " - Compiling Downloader.java ..."
  "$(native_path "$JAVACCMD")" "$(native_path "$javaSource")" || die "Failed to compile Downloader.java"
  verbose " - Running Downloader.java ..."
  "$(native_path "$JAVACMD")" -cp "$(native_path "$TMP_DOWNLOAD_DIR")" Downloader "$distributionUrl" "$(native_path "$targetZip")"
fi

# If specified, validate the SHA-256 sum of the Maven distribution zip file
if [ -n "${distributionSha256Sum-}" ]; then
  distributionSha256Result=false
  if [ "$MVN_CMD" = mvnd.sh ]; then
    echo "Checksum validation is not supported for maven-mvnd." >&2
    echo "Please disable validation by removing 'distributionSha256Sum' from your maven-wrapper.properties." >&2
    exit 1
  elif command -v sha256sum >/dev/null; then
    if echo "$distributionSha256Sum  $TMP_DOWNLOAD_DIR/$distributionUrlName" | sha256sum -c - >/dev/null 2>&1; then
      distributionSha256Result=true
    fi
  elif command -v shasum >/dev/null; then
    if echo "$distributionSha256Sum  $TMP_DOWNLOAD_DIR/$distributionUrlName" | shasum -a 256 -c >/dev/null 2>&1; then
      distributionSha256Result=true
    fi
  else
    echo "Checksum validation was requested but neither 'sha256sum' or 'shasum' are available." >&2
    echo "Please install either command, or disable validation by removing 'distributionSha256Sum' from your maven-wrapper.properties." >&2
    exit 1
  fi
  if [ $distributionSha256Result = false ]; then
    echo "Error: Failed to validate Maven distribution SHA-256, your Maven distribution might be compromised." >&2
    echo "If you updated your Maven version, you need to update the specified distributionSha256Sum property." >&2
    exit 1
  fi
fi

# unzip and move
if command -v unzip >/dev/null; then
  unzip ${__MVNW_QUIET_UNZIP:+"$__MVNW_QUIET_UNZIP"} "$TMP_DOWNLOAD_DIR/$distributionUrlName" -d "$TMP_DOWNLOAD_DIR" || die "failed to unzip"
else
  tar xzf${__MVNW_QUIET_TAR:+"$__MVNW_QUIET_TAR"} "$TMP_DOWNLOAD_DIR/$distributionUrlName" -C "$TMP_DOWNLOAD_DIR" || die "failed to untar"
fi

# Find the actual extracted directory name (handles snapshots where filename != directory name)
actualDistributionDir=""

# First try the expected directory name (for regular distributions)
if [ -d "$TMP_DOWNLOAD_DIR/$distributionUrlNameMain" ]; then
  if [ -f "$TMP_DOWNLOAD_DIR/$distributionUrlNameMain/bin/$MVN_CMD" ]; then
    actualDistributionDir="$distributionUrlNameMain"
  fi
fi

# If not found, search for any directory with the Maven executable (for snapshots)
if [ -z "$actualDistributionDir" ]; then
  # enable globbing to iterate over items
  set +f
  for dir in "$TMP_DOWNLOAD_DIR"/*; do
    if [ -d "$dir" ]; then
      if [ -f "$dir/bin/$MVN_CMD" ]; then
        actualDistributionDir="$(basename "$dir")"
        break
      fi
    fi
  done
  set -f
fi

if [ -z "$actualDistributionDir" ]; then
  verbose "Contents of $TMP_DOWNLOAD_DIR:"
  verbose "$(ls -la "$TMP_DOWNLOAD_DIR")"
  die "Could not find Maven distribution directory in extracted archive"
fi

verbose "Found extracted Maven distribution directory: $actualDistributionDir"
printf %s\\n "$distributionUrl" >"$TMP_DOWNLOAD_DIR/$actualDistributionDir/mvnw.url"
mv -- "$TMP_DOWNLOAD_DIR/$actualDistributionDir" "$MAVEN_HOME" || [ -d "$MAVEN_HOME" ] || die "fail to move MAVEN_HOME"

clean || :
exec_maven "$@"

Step 3. Create mvnw.cmd:

<# : batch portion
@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    http://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 Apache Maven Wrapper startup batch script, version 3.3.4
@REM
@REM Optional ENV vars
@REM   MVNW_REPOURL - repo url base for downloading maven distribution
@REM   MVNW_USERNAME/MVNW_PASSWORD - user and password for downloading maven
@REM   MVNW_VERBOSE - true: enable verbose log; others: silence the output
@REM ----------------------------------------------------------------------------

@IF "%__MVNW_ARG0_NAME__%"=="" (SET __MVNW_ARG0_NAME__=%~nx0)
@SET __MVNW_CMD__=
@SET __MVNW_ERROR__=
@SET __MVNW_PSMODULEP_SAVE=%PSModulePath%
@SET PSModulePath=
@FOR /F "usebackq tokens=1* delims==" %%A IN (`powershell -noprofile "& {$scriptDir='%~dp0'; $script='%__MVNW_ARG0_NAME__%'; icm -ScriptBlock ([Scriptblock]::Create((Get-Content -Raw '%~f0'))) -NoNewScope}"`) DO @(
  IF "%%A"=="MVN_CMD" (set __MVNW_CMD__=%%B) ELSE IF "%%B"=="" (echo %%A) ELSE (echo %%A=%%B)
)
@SET PSModulePath=%__MVNW_PSMODULEP_SAVE%
@SET __MVNW_PSMODULEP_SAVE=
@SET __MVNW_ARG0_NAME__=
@SET MVNW_USERNAME=
@SET MVNW_PASSWORD=
@IF NOT "%__MVNW_CMD__%"=="" ("%__MVNW_CMD__%" %*)
@echo Cannot start maven from wrapper >&2 && exit /b 1
@GOTO :EOF
: end batch / begin powershell #>

$ErrorActionPreference = "Stop"
if ($env:MVNW_VERBOSE -eq "true") {
  $VerbosePreference = "Continue"
}

# calculate distributionUrl, requires .mvn/wrapper/maven-wrapper.properties
$distributionUrl = (Get-Content -Raw "$scriptDir/.mvn/wrapper/maven-wrapper.properties" | ConvertFrom-StringData).distributionUrl
if (!$distributionUrl) {
  Write-Error "cannot read distributionUrl property in $scriptDir/.mvn/wrapper/maven-wrapper.properties"
}

switch -wildcard -casesensitive ( $($distributionUrl -replace '^.*/','') ) {
  "maven-mvnd-*" {
    $USE_MVND = $true
    $distributionUrl = $distributionUrl -replace '-bin\.[^.]*$',"-windows-amd64.zip"
    $MVN_CMD = "mvnd.cmd"
    break
  }
  default {
    $USE_MVND = $false
    $MVN_CMD = $script -replace '^mvnw','mvn'
    break
  }
}

# apply MVNW_REPOURL and calculate MAVEN_HOME
# maven home pattern: ~/.m2/wrapper/dists/{apache-maven-<version>,maven-mvnd-<version>-<platform>}/<hash>
if ($env:MVNW_REPOURL) {
  $MVNW_REPO_PATTERN = if ($USE_MVND -eq $False) { "/org/apache/maven/" } else { "/maven/mvnd/" }
  $distributionUrl = "$env:MVNW_REPOURL$MVNW_REPO_PATTERN$($distributionUrl -replace "^.*$MVNW_REPO_PATTERN",'')"
}
$distributionUrlName = $distributionUrl -replace '^.*/',''
$distributionUrlNameMain = $distributionUrlName -replace '\.[^.]*$','' -replace '-bin$',''

$MAVEN_M2_PATH = "$HOME/.m2"
if ($env:MAVEN_USER_HOME) {
  $MAVEN_M2_PATH = "$env:MAVEN_USER_HOME"
}

if (-not (Test-Path -Path $MAVEN_M2_PATH)) {
    New-Item -Path $MAVEN_M2_PATH -ItemType Directory | Out-Null
}

$MAVEN_WRAPPER_DISTS = $null
if ((Get-Item $MAVEN_M2_PATH).Target[0] -eq $null) {
  $MAVEN_WRAPPER_DISTS = "$MAVEN_M2_PATH/wrapper/dists"
} else {
  $MAVEN_WRAPPER_DISTS = (Get-Item $MAVEN_M2_PATH).Target[0] + "/wrapper/dists"
}

$MAVEN_HOME_PARENT = "$MAVEN_WRAPPER_DISTS/$distributionUrlNameMain"
$MAVEN_HOME_NAME = ([System.Security.Cryptography.SHA256]::Create().ComputeHash([byte[]][char[]]$distributionUrl) | ForEach-Object {$_.ToString("x2")}) -join ''
$MAVEN_HOME = "$MAVEN_HOME_PARENT/$MAVEN_HOME_NAME"

if (Test-Path -Path "$MAVEN_HOME" -PathType Container) {
  Write-Verbose "found existing MAVEN_HOME at $MAVEN_HOME"
  Write-Output "MVN_CMD=$MAVEN_HOME/bin/$MVN_CMD"
  exit $?
}

if (! $distributionUrlNameMain -or ($distributionUrlName -eq $distributionUrlNameMain)) {
  Write-Error "distributionUrl is not valid, must end with *-bin.zip, but found $distributionUrl"
}

# prepare tmp dir
$TMP_DOWNLOAD_DIR_HOLDER = New-TemporaryFile
$TMP_DOWNLOAD_DIR = New-Item -Itemtype Directory -Path "$TMP_DOWNLOAD_DIR_HOLDER.dir"
$TMP_DOWNLOAD_DIR_HOLDER.Delete() | Out-Null
trap {
  if ($TMP_DOWNLOAD_DIR.Exists) {
    try { Remove-Item $TMP_DOWNLOAD_DIR -Recurse -Force | Out-Null }
    catch { Write-Warning "Cannot remove $TMP_DOWNLOAD_DIR" }
  }
}

New-Item -Itemtype Directory -Path "$MAVEN_HOME_PARENT" -Force | Out-Null

# Download and Install Apache Maven
Write-Verbose "Couldn't find MAVEN_HOME, downloading and installing it ..."
Write-Verbose "Downloading from: $distributionUrl"
Write-Verbose "Downloading to: $TMP_DOWNLOAD_DIR/$distributionUrlName"

$webclient = New-Object System.Net.WebClient
if ($env:MVNW_USERNAME -and $env:MVNW_PASSWORD) {
  $webclient.Credentials = New-Object System.Net.NetworkCredential($env:MVNW_USERNAME, $env:MVNW_PASSWORD)
}
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
$webclient.DownloadFile($distributionUrl, "$TMP_DOWNLOAD_DIR/$distributionUrlName") | Out-Null

# If specified, validate the SHA-256 sum of the Maven distribution zip file
$distributionSha256Sum = (Get-Content -Raw "$scriptDir/.mvn/wrapper/maven-wrapper.properties" | ConvertFrom-StringData).distributionSha256Sum
if ($distributionSha256Sum) {
  if ($USE_MVND) {
    Write-Error "Checksum validation is not supported for maven-mvnd. `nPlease disable validation by removing 'distributionSha256Sum' from your maven-wrapper.properties."
  }
  Import-Module $PSHOME\Modules\Microsoft.PowerShell.Utility -Function Get-FileHash
  if ((Get-FileHash "$TMP_DOWNLOAD_DIR/$distributionUrlName" -Algorithm SHA256).Hash.ToLower() -ne $distributionSha256Sum) {
    Write-Error "Error: Failed to validate Maven distribution SHA-256, your Maven distribution might be compromised. If you updated your Maven version, you need to update the specified distributionSha256Sum property."
  }
}

# unzip and move
Expand-Archive "$TMP_DOWNLOAD_DIR/$distributionUrlName" -DestinationPath "$TMP_DOWNLOAD_DIR" | Out-Null

# Find the actual extracted directory name (handles snapshots where filename != directory name)
$actualDistributionDir = ""

# First try the expected directory name (for regular distributions)
$expectedPath = Join-Path "$TMP_DOWNLOAD_DIR" "$distributionUrlNameMain"
$expectedMvnPath = Join-Path "$expectedPath" "bin/$MVN_CMD"
if ((Test-Path -Path $expectedPath -PathType Container) -and (Test-Path -Path $expectedMvnPath -PathType Leaf)) {
  $actualDistributionDir = $distributionUrlNameMain
}

# If not found, search for any directory with the Maven executable (for snapshots)
if (!$actualDistributionDir) {
  Get-ChildItem -Path "$TMP_DOWNLOAD_DIR" -Directory | ForEach-Object {
    $testPath = Join-Path $_.FullName "bin/$MVN_CMD"
    if (Test-Path -Path $testPath -PathType Leaf) {
      $actualDistributionDir = $_.Name
    }
  }
}

if (!$actualDistributionDir) {
  Write-Error "Could not find Maven distribution directory in extracted archive"
}

Write-Verbose "Found extracted Maven distribution directory: $actualDistributionDir"
Rename-Item -Path "$TMP_DOWNLOAD_DIR/$actualDistributionDir" -NewName $MAVEN_HOME_NAME | Out-Null
try {
  Move-Item -Path "$TMP_DOWNLOAD_DIR/$MAVEN_HOME_NAME" -Destination $MAVEN_HOME_PARENT | Out-Null
} catch {
  if (! (Test-Path -Path "$MAVEN_HOME" -PathType Container)) {
    Write-Error "fail to move MAVEN_HOME"
  }
} finally {
  try { Remove-Item $TMP_DOWNLOAD_DIR -Recurse -Force | Out-Null }
  catch { Write-Warning "Cannot remove $TMP_DOWNLOAD_DIR" }
}

Write-Output "MVN_CMD=$MAVEN_HOME/bin/$MVN_CMD"

Step 4. Verify:

mvn clean test
# BUILD SUCCESS - no tests yet

Step 5. Commit:

git add -A
git commit -F- <<'EOF'
build: add a Maven wrapper pinned to 3.9.16

A reviewer can now build with ./mvnw and get the same Maven version the
project was developed against, without installing one.
EOF

5 · ignore the state file the application writes

chore · 3d1c605

Why

Running the application writes libraryState.txt into the working directory. It is runtime state, not source, and must never be committed.

Step 1. In .gitignore, find:

# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
hs_err_pid*
replay_pid*

and replace it with:

# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
hs_err_pid*
replay_pid*

# Runtime state written by the application
libraryState.txt

Step 2. Verify:

mvn clean test
# BUILD SUCCESS - no tests yet

Step 3. Commit:

git add -A
git commit -F- <<'EOF'
chore: ignore the state file the application writes

Running the application writes libraryState.txt into the working
directory. It is runtime state, not source, and must never be committed.
EOF