* undergone any updates by the model builder, e.g. reflects neither inheritance nor interpolation. The model
     * identifier should be from the collection obtained by {@link #getModelIds()}. As a special case, an empty string
     * can be used as the identifier for the super POM.
     *
     * @param modelId The identifier of the desired raw model, must not be {@code null}.

        props.putAll(getSystemProperties());
    }

    /**
     * Returns a copy of {@link System#getProperties()} in a thread-safe manner.
     *
     * @return {@link System#getProperties()} obtained in a thread-safe manner.
     */
    public static Properties getSystemProperties() {
        return copyProperties(System.getProperties());
    }

    /**

     *         <code>null</code>. If it is <code>null</code>, the specified version range's recommended
     *         version is used (provided it is non-<code>null</code>). If no recommended version can be
     *         obtained, the returned version range's recommended version is set to <code>null</code>.
     *         </p>
     * @throws NullPointerException if the specified <code>VersionRange</code> is

     */
    @Nonnull
    Optional<Source> locate(@Nonnull Path dir);

    /**
     * Parse the model obtained previously by a previous call to {@link #locate(Path)}.
     *
     * @param source the source to parse, never {@code null}
     * @param options possible parsing options, may be {@code null}