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.

    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));
    }

    /**

                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(

        project.getPlugins().apply(InternalTestArtifactBasePlugin.class);
        InternalTestArtifactExtension testArtifactExtension = project.getExtensions().getByType(InternalTestArtifactExtension.class);
        SourceSet testSourceSet = project.getExtensions().getByType(SourceSetContainer.class).getByName("test");
        testArtifactExtension.registerTestArtifactFromSourceSet(testSourceSet);
    }

                    (name, port) -> task.getExtensions().getByType(ExtraPropertiesExtension.class).set(name, port)
                );
            });

            maybeSkipTask(dockerSupport, preProcessFixture);
            maybeSkipTask(dockerSupport, postProcessFixture);
            maybeSkipTask(dockerSupport, buildFixture);

            ComposeExtension composeExtension = project.getExtensions().getByType(ComposeExtension.class);

        project.getTasks().register("buildResources", ExportElasticsearchBuildResourcesTask.class);

        // only setup tests to build
        SourceSetContainer sourceSets = project.getExtensions().getByType(SourceSetContainer.class);
        final SourceSet testSourceSet = sourceSets.create("test");

        project.getTasks().withType(Test.class).configureEach(test -> {

            @SuppressWarnings("unchecked")
            NamedDomainObjectContainer<ElasticsearchCluster> testClusters = (NamedDomainObjectContainer<ElasticsearchCluster>) project
                .getExtensions()
                .getByName(TestClustersPlugin.EXTENSION_NAME);
            ElasticsearchCluster cluster = testClusters.maybeCreate(restIntegTestTask.getName());
            restIntegTestTask.useCluster(cluster);

     }

    /**
     * Adds compiler settings to the project
     */
    public static void configureCompile(Project project) {
        project.getExtensions().getExtraProperties().set("compactProfile", "full");

        JavaPluginExtension java = project.getExtensions().getByType(JavaPluginExtension.class);
        java.setSourceCompatibility(BuildParams.getMinimumRuntimeVersion());