public static Properties getSystemProperties() {
        return copyProperties(System.getProperties());
    }

    /**
     * Copies the given {@link Properties} object into a new {@link Properties} object, in a thread-safe manner.
     * @param properties Properties to copy.
     * @return Copy of the given properties.
     */
    public static Properties copyProperties(Properties properties) {

    }

    @Override
    public ProjectBuildingRequest setSystemProperties(Properties systemProperties) {
        if (systemProperties != null) {
            this.systemProperties = SystemProperties.copyProperties(systemProperties);
        } else {
            this.systemProperties.clear();
        }

        return this;
    }

    @Override
    public Properties getUserProperties() {

        return this;
    }

    @Override
    public MavenExecutionRequest setSystemProperties(Properties properties) {
        if (properties != null) {
            this.systemProperties = SystemProperties.copyProperties(properties);
        } else {
            this.systemProperties = null;
        }

        return this;
    }

    @Override