<dependencies>
    <dependency>
      <groupId>com.sun</groupId>
      <artifactId>tools</artifactId>
      <version>1.4.2</version>
      <scope>system</scope>
      <systemPath>${jre.home}/../lib/tools.jar</systemPath>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.its.plugins</groupId>

# For Cygwin and MinGW, switch paths to Windows format before running java(1) command
if $cygwin || $mingw ; then
  [ -n "$JAVA_HOME" ] &&
    JAVA_HOME=`cygpath --windows "$JAVA_HOME"`
  LAUNCHER_JAR=`cygpath --windows "$LAUNCHER_JAR"`
  CLASSWORLDS_CONF=`cygpath --windows "$CLASSWORLDS_CONF"`
  MAVEN_HOME=`cygpath --windows "$MAVEN_HOME"`
  MAVEN_PROJECTBASEDIR=`cygpath --windows "$MAVEN_PROJECTBASEDIR"`
fi

exec "$JAVACMD" \
  $MAVEN_OPTS \

set maven.conf default ${maven.home}/conf

[plexus.core]
load       ${maven.conf}/logging
optionally ${maven.home}/lib/ext/redisson/*.jar
optionally ${maven.home}/lib/ext/hazelcast/*.jar
optionally ${user.home}/.m2/ext/*.jar
optionally ${maven.home}/lib/ext/*.jar
load       ${maven.home}/lib/maven-*.jar

@REM ==== START VALIDATION ====
if not "%JAVA_HOME%"=="" goto javaHomeSet
for %%i in (java.exe) do set "JAVACMD=%%~$PATH:i"
goto checkJavaCmd

:javaHomeSet
set "JAVACMD=%JAVA_HOME%\bin\java.exe"

if not exist "%JAVACMD%" (
  echo The JAVA_HOME environment variable is not defined correctly, so Apache Maven cannot be started. >&2
  echo JAVA_HOME is set to "%JAVA_HOME%", but "%%JAVA_HOME%%\bin\java.exe" does not exist. >&2
  goto error
)

@REM ==== END VALIDATION ====

:init

set "CLASSWORLDS_CONF=%MAVEN_HOME%\bin\m2.conf"

@REM Find the project basedir, i.e., the directory that contains the directory ".mvn".
@REM Fallback to current working directory if not found.

set "EXEC_DIR=%CD%"
set "WDIR=%EXEC_DIR%"

@REM Look for the --file switch and start the search for the .mvn directory from the specified
@REM POM location, if supplied.

set FILE_ARG=
:arg_loop

LAUNCHER_JAR=`echo "$MAVEN_HOME"/boot/plexus-classworlds-*.jar`

7d32e7520b801cabc3dc704d2afe59d020d00c45  /home/projects/maven/repository-staging/to-ibiblio/maven2/commons-logging/commons-logging/1.0.4/commons-logging-1.0.4.pom...

        this.settingsBuilder = settingsBuilder;
    }

    public Settings buildSettings() throws IOException, XmlPullParserException {
        File userSettingsFile = getFile(
                "${user.home}/.m2/settings.xml", "user.home", MavenSettingsBuilder.ALT_USER_SETTINGS_XML_LOCATION);

        return buildSettings(userSettingsFile);
    }

 not sure the unified source directory structure addresses this issue.

 Properties

 maven.user.config.dir (system,default=${user.home}/.m2)
 maven.home            (system,user,default=${user.home}/m2)
 maven.repo.local      (system,user,default=${maven.user.config.dir}/repository)

 We need to define what happens in the when things are not setup correctly

    <repository>
      <id>repo1</id>
      <name>Maven Central Repository</name>
      <url>scp://repo1.maven.org/home/projects/maven/repository-staging/to-ibiblio/maven2</url>
    </repository>
    <snapshotRepository>
      <id>snapshots</id>
      <name>Maven Central Development Repository</name>
      <url>scp://repo1.maven.org/home/projects/maven/repository-staging/snapshots/maven2</url>
    </snapshotRepository>
  </distributionManagement>