ArtifactTransferEvent event = wrap(transferEvent);

        Long transferred;
        synchronized (transfers) {
            transferred = transfers.remove(transferEvent.getResource());
        }
        if (transferred != null) {
            event.setTransferredBytes(transferred);
        }

        synchronized (artifacts) {
            artifacts.remove(transferEvent.getResource());
        }

        }
    }

    public void markForDeletion(File toDelete) {
        filesToDelete.add(toDelete);
        warnAboutCleanup = true;
    }

    public synchronized File createTempDir() {
        try {
            Thread.sleep(20);
        } catch (InterruptedException e) {
            // ignore
        }

</p>

<p>
The <i>synchronized before</i> relation is a partial order on synchronizing memory operations,
derived from <i>W</i>.
If a synchronizing read-like memory operation <i>r</i>
observes a synchronizing write-like memory operation <i>w</i>
(that is, if <i>W</i>(<i>r</i>) = <i>w</i>),
then <i>w</i> is synchronized before <i>r</i>.
Informally, the synchronized before relation is a subset of the implied total order

    }

    // gather artifactIds which are not unique so that the respective thread names can be extended with the groupId
    public Set<String> duplicateIds() {
        if (duplicateIds == null) {
            synchronized (this) {
                if (duplicateIds == null) {
                    duplicateIds = projects()
                            .map(MavenProject::getArtifactId)

type Writer struct {
	// opts are the configuration options for this Writer
	opts Options

	// f is the currently open file used for appends.
	// Writes to f are only synchronized once Close() is called,
	// or when files are being rotated.
	f *os.File

	pw *xioutil.PipeWriter
	pr *xioutil.PipeReader
}

// Write writes p into the current file, rotating if necessary.

        this.delegates = delegates;
        this.coreArtifacts = coreExports.getExportedArtifacts();
    }

    private synchronized Set<String> getExcludedArtifacts() {
        if (excludedArtifacts == null) {
            excludedArtifacts = new LinkedHashSet<>(coreArtifacts);
        }
        return excludedArtifacts;
    }

    /**

            this.pluginDeclarations = new LinkedHashSet<>();
            this.pluginIssues = new HashMap<>();
            this.mojoIssues = new HashMap<>();
        }

        private synchronized void reportPluginIssue(
                IssueLocality issueLocality, String pluginDeclaration, String issue) {
            if (pluginDeclaration != null) {
                pluginDeclarations.add(pluginDeclaration);

            throws PluginDescriptorParsingException, PluginResolutionException, InvalidPluginDescriptorException {

        PluginDescriptor desc = descriptors.get(key);
        if (desc == null) {
            synchronized (key) {
                desc = descriptors.get(key);
                if (desc == null) {
                    desc = supplier.load();
                    descriptors.putIfAbsent(key, clone(desc));
                }

    }

    @Override
    public void setFile(File file) {
        throw new UnsupportedOperationException("transformed artifact file cannot be set");
    }

    @Override
    public synchronized File getFile() {
        try {
            String state = mayUpdate();
            if (state == null) {
                return null;
            }
            return target.toFile();

                synchronized (result) {
                    result.addMissingArtifact(artifact);
                }
            } catch (ArtifactResolutionException e) {
                // This is really a wagon TransferFailedException so something went wrong after we successfully
                // retrieved the metadata.

                synchronized (result) {