Properties props = new Properties();
        props.putAll(getter.get());
        T ret = runner.perform(props);
        if (!props.equals(getter.get())) {
            setter.accept(props);
        }
        return ret;
    }

    private void writeOperationVoid(WriteOpVoid runner) {
        Properties props = new Properties();
        props.putAll(getter.get());
        runner.perform(props);

            if (sourceDominant) {
                merged.putAll(target.getProperties());
                putAll(merged, source.getProperties(), CHILD_DIRECTORY_PROPERTY);
            } else {
                putAll(merged, source.getProperties(), CHILD_DIRECTORY_PROPERTY);
                merged.putAll(target.getProperties());
            }
            builder.properties(merged);

        } else if (targetLocations == null) {
            locations = sourceLocations;
        } else {
            locations = new LinkedHashMap<>();
            locations.putAll(sourceDominant ? targetLocations : sourceLocations);
            locations.putAll(sourceDominant ? sourceLocations : targetLocations);
        }

        return new InputLocation(target.getLineNumber(), target.getColumnNumber(), target.getSource(), locations);

                contributor.contribute(userPropertiesMap);
            }
            Properties newProperties = new Properties();
            newProperties.putAll(userPropertiesMap);
            mavenExecutionRequest.setUserProperties(newProperties);
        }
    }

        HashMap<String, String> result = new HashMap<>(getSystemProperties());
        if (project != null) {
            result.putAll(project.getModel().getProperties());
        }
        result.putAll(getUserProperties());
        return result;
    }

    @Nonnull
    @Override
    public Version getMavenVersion() {

        this.repositorySystemSession = requireNonNull(repositorySystemSession);
        Properties executionProperties = new Properties();
        executionProperties.putAll(request.getSystemProperties());
        executionProperties.putAll(request.getUserProperties());
        this.executionProperties = executionProperties;
    }

    @Deprecated
    public MavenSession(
            PlexusContainer container,

            if (sourceDominant) {
                merged.putAll(target.getProperties());
                putAll(merged, source.getProperties(), CHILD_DIRECTORY_PROPERTY);
            } else {
                putAll(merged, source.getProperties(), CHILD_DIRECTORY_PROPERTY);
                merged.putAll(target.getProperties());
            }
            builder.properties(merged);

        Properties props = new Properties();
        if (recessive != null) {
            props.putAll(recessive);
        }
        if (dominant != null) {
            props.putAll(dominant);
        }
        return props;
    }

    private Artifact getRelocation(

        Map<String, String> props = new HashMap<>();
        if (recessive != null) {
            props.putAll(recessive);
        }
        if (dominant != null) {
            props.putAll(dominant);
        }
        return props;
    }

    private Artifact getRelocation(

    }

    private static class ROProperties extends Properties {
        private ROProperties(Properties props) {
            super();
            if (props != null) {
                // Do not use super.putAll, as it may delegate to put which throws an UnsupportedOperationException
                for (Map.Entry<Object, Object> e : props.entrySet()) {
                    super.put(e.getKey(), e.getValue());
                }