build.sh

if [[ -z ${JAVA_HOME} ]]; then
    echo "JAVA_HOME is not set"
    exit 1
fi

jdk_version() {
    local result
    local java_cmd=$JAVA_HOME/bin/java
    local IFS=$'\n'
    # remove \r for Cygwin
    local lines=$("$java_cmd" -Xms32M -Xmx32M -version 2>&1 | tr '\r' '\n')
    if [[ -z $java_cmd ]]
    then
        result=no_java
    else
        for line in $lines; do
            if [[ (-z $result) && ($line = *"version \""*) ]]
            then
                local ver=$(echo $line | sed -e 's/.*version "\(.*\)"\(.*\)/\1/; 1q')
                # on macOS, sed doesn't support '?'
                if [[ $ver = "1."* ]]
                then
                    result=$(echo $ver | sed -e 's/1\.\([0-9]*\)\(.*\)/\1/; 1q')
                else
                    result=$(echo $ver | sed -e 's/\([0-9]*\)\(.*\)/\1/; 1q')
                fi
            fi
        done
    fi
    echo "$result"
}

JAVA_VERSION=$(jdk_version)
if [[ "$JAVA_VERSION" -ne "11" ]]; then
    echo "must use jdk11 to compile"
    exit 1
fi

mvn package