getExtensions().remove(coreExtension);
    } // -- void removeExtension( CoreExtension )

    /**
     * Set a set of build extensions to use from this project.
     *
     * @param extensions a extensions object.
     */
    public void setExtensions(List<CoreExtension> extensions) {
        this.extensions = extensions;
    } // -- void setExtensions( List )

    /**
     * Set the modelEncoding field.

                java.util.List<CoreExtension> extensions = coreExtensions.getExtensions();
                if (extensions == null) {
                    extensions = new java.util.ArrayList<CoreExtension>();
                }
                extensions.add(parseCoreExtension(parser, strict));
                coreExtensions.setExtensions(extensions);
            } else {
                checkUnknownElement(parser, strict);

                if (org != val) {
                    plugin.setVersion(val);
                }
                // Extensions
                org = plugin.getExtensions();
                val = interpolate(org);
                if (org != val) {
                    plugin.setExtensions(val);
                }
                // Executions
                for (PluginExecution execution : plugin.getExecutions()) {

        }
    }

    protected void mergeBuild_Extensions(
            Build target, Build source, boolean sourceDominant, Map<Object, Object> context) {
        target.setExtensions(
                merge(target.getExtensions(), source.getExtensions(), sourceDominant, new ExtensionKeyComputer()));
    }

    protected void mergeExtension(

    public boolean isExtensions() {
        return (getExtensions() != null) ? Boolean.parseBoolean(getExtensions()) : false;
    }
            ]]>
          </code>
        </codeSegment>
        <codeSegment>
          <version>4.0.0/4.0.99</version>
          <code>
            <![CDATA[
    public void setExtensions(boolean extensions) {
        setExtensions(String.valueOf(extensions));
    }

    /**

                "http://maven.apache.org/EXTENSIONS/1.1.0 https://maven.apache.org/xsd/core-extensions-1.1.0.xsd");
        if ((coreExtensions.getExtensions() != null)
                && (coreExtensions.getExtensions().size() > 0)) {
            for (Iterator iter = coreExtensions.getExtensions().iterator(); iter.hasNext(); ) {
                CoreExtension o = (CoreExtension) iter.next();

        List<Plugin> extensionPlugins = new ArrayList<>();

        Build build = model.getBuild();

        if (build != null) {
            for (Extension extension : build.getExtensions()) {
                Plugin plugin = new Plugin();
                plugin.setGroupId(extension.getGroupId());
                plugin.setArtifactId(extension.getArtifactId());

        public void setVersion(String version) {
            this.version = version;
        }

        public String getExtension() {
            return extension;
        }

        public void setExtension(String extension) {
            this.extension = extension;
        }

        public String getClassifier() {
            return classifier;
        }

                            List.copyOf(new CoreExtensionsStaxReader()
                                    .read(is, true, InputSource.of(extensionsFile.toString()))
                                    .getExtensions()),
                            allowMetaVersions);
                }
            }
            return List.of();
        } catch (XMLStreamException | IOException e) {

                            EMPTY,
                            problems,
                            errOn30,
                            Version.V20,
                            p.getExtensions(),
                            p.getKey(),
                            p);

                    validate20EffectivePluginDependencies(problems, p, request);
                }