}

    /**
     * Take the value if this is a left.
     */
    public abstract Optional<L> getLeft();

    /**
     * Take the value if this is a right.
     */
    public abstract Optional<R> getRight();

    /**
     * Map the left side.
     *
     * @see #mapRight
     * @see #fold
     */
    public abstract <U, V> Either<U, V> mapLeft(Function<? super L, ? extends U> f);

    /**

                return person;
            }
        }
        return null;
    }

    public static Person of(Pair<String, String> pair) {
        return new Person(pair.getLeft(), pair.getRight());
    }

                return person;
            }
        }
        return null;
    }

    public static Person of(Pair<String, String> pair) {
        return new Person(pair.getLeft(), pair.getRight());
    }

            if (match != null) {
                match = Pair.of(withoutDebug, match.getRight());
            } else {
                // Not present, assume no failure details
                match = Pair.of(withoutDebug, LogContent.empty());
            }
        } else {
            if (match.getRight().countMatches(FAILURE_PATTERN) != 1) {

        this.left = left;
        this.right = right;
    }

    public AbstractFileCollection getLeft() {
        return left;
    }

    public FileCollection getRight() {
        return right;
    }

    @Override
    public String getDisplayName() {
        return "file collection";
    }

    @Override

        // Only merge if about the same capability, otherwise last wins
        if (this.capabilityReject.getLeft().equals(capability)) {
            this.capabilityReject.getRight().addAll(conflictedNodes);
        } else {
            this.capabilityReject = Pair.of(capability, conflictedNodes);
        }
    }

    @Override
    public boolean isRejected() {

        this.left = left;
        this.right = right;
    }

    @Nullable
    public L getLeft() {
        return left;
    }

    @Nullable
    public R getRight() {
        return right;
    }

    @Nullable
    public L left() {
        return left;
    }

    @Nullable
    public R right() {
        return right;
    }

    }

    private static <T> boolean isIncubating(Pair<Attribute<T>, T> attributePair) {
        return isIncubating(Objects.requireNonNull(attributePair.getLeft()), attributePair.getRight());
    }

    private static <T> boolean isIncubatingAttributeInterface(Attribute<T> key) {
        return isAnnotatedWithIncubating(key.getType());
    }

        for (Pair<ModuleVersionIdentifier, ProjectComponentIdentifier> replacement : replacements) {
            replacementMap.put(replacement.getLeft().getModule(), replacement.getRight());
        }
    }

    @Override
    public void execute(DependencySubstitution sub) {
        DependencySubstitutionInternal dependencySubstitution = (DependencySubstitutionInternal) sub;

    }

    public Optional<Enabled> whenEnabled() {
        return delegate.getLeft();
    }

    public Optional<Disabled> whenDisabled() {
        return delegate.getRight();
    }

    public <T> T fold(Function<Enabled, T> enabled, Function<Disabled, T> disabled) {
        return delegate.fold(enabled, disabled);
    }