/**
     * Gets the system properties to use for interpolation and profile activation. The system properties are collected
     * from the runtime environment like {@link System#getProperties()} and environment variables.
     *
     * @return The execution properties, never {@code null}.
     */
    Map<String, String> getSystemProperties();

    /**

                        relocation.global ? "User global relocation" : "User project relocation");
                LOGGER.debug(
                        "The artifact {} has been relocated to {}: {}",
                        original,
                        result,
                        relocation.global ? "User global relocation" : "User project relocation");
                return result;
            }
        }

        Source userSource = request.getUserToolchainsSource().orElse(null);
        PersistedToolchains user = readToolchains(userSource, request, problems);

        PersistedToolchains effective = toolchainsMerger.merge(user, global, false, null);

        if (hasErrors(problems)) {
            throw new ToolchainsBuilderException("Error building toolchains", problems);
        }

    /**
     * Returns immutable user properties to use for interpolation. The user properties have been configured directly
     * by the user, e.g. via the {@code -Dkey=value} parameter on the command line.
     *
     * @return the user properties, never {@code null}
     */
    @Nonnull
    Map<String, String> getUserProperties();

    /**

     *
     * @return the global Toolchains source or {@code null} if none
     */
    @Nonnull
    Optional<Source> getGlobalToolchainsSource();

    /**
     * Gets the user Toolchains source.
     *
     * @return the user Toolchains source or {@code null} if none
     */
    @Nonnull
    Optional<Source> getUserToolchainsSource();

    @Nonnull
    static ToolchainsBuilderRequest build(

 * <tr><td><code>basedir</code></td>           <td></td>
 *                                             <td>{@link MavenSession#getExecutionRootDirectory()} or
 *                                                 <code>System.getProperty( "user.dir" )</code> if null</td></tr>
 * <tr><td><code>mojoExecution</code></td>     <td></td>               <td>the actual {@link MojoExecution}</td></tr>

            // The root locator can be used very early during the setup of Maven,
            // even before the arguments from the command line are parsed.  Any exception
            // that would happen here should cause the build to fail at a later stage
            // (when actually parsing the POM) and will lead to a better exception being
            // displayed to the user, so just bail out and return false.
        }

    /**
     * Specifies that this parameter cannot be configured directly by the user (as in the case of POM-specified
     * configuration). This is useful when you want to force the user to use common POM elements rather than plugin
     * configurations, as in the case where you want to use the artifact's final name as a parameter. In this case, you

     *
     * @param phase
     * @return
     */
    public Lifecycle get(String phase) {
        return getPhaseToLifecycleMap().get(phase);
    }

    /**
     * We use this to map all phases to the lifecycle that contains it. This is used so that a user can specify the
     * phase they want to execute and we can easily determine what lifecycle we need to run.
     *
     * @return A map of lifecycles, indexed on id
     */

/**
 * Component able to contribute to Maven session user properties. This SPI component is invoked
 * very early, while there is no session created yet.
 *
 * @since 4.0.0
 */
@Experimental
@Consumer
public interface PropertyContributor extends SpiService {
    /**
     * Invoked just before session is created with a mutable map that carries collected user properties so far.
     *