* directory pointed at by the {@code -f/--file} command line argument.
     */
    @Nonnull
    Path getTopDirectory();

    /**
     * Gets the root directory of the session, which is the root directory for the top directory project.
     *
     * @throws IllegalStateException if the root directory could not be found
     * @see #getTopDirectory()
     * @see Project#getRootDirectory()
     */
    @Nonnull

    void setDegreeOfConcurrency(int degreeOfConcurrency);

    /**
     * @return the degree of concurrency for the build.
     */
    int getDegreeOfConcurrency();

    // Recursive (really to just process the top-level POM)
    MavenExecutionRequest setRecursive(boolean recursive);

    boolean isRecursive();

    MavenExecutionRequest setPom(File pom);

    File getPom();

    // Errors

     * filter is applied (like in Maven 3).
     * <p>
     * Supported filters:
     * <ul>
     *     <li>"h" or "h(num)" - highest version or top list of highest ones filter</li>
     *     <li>"l" or "l(num)" - lowest version or bottom list of lowest ones filter</li>
     *     <li>"s" - contextual snapshot filter</li>