* packages and resources are visible.
 */
public class FilteringClassLoader extends ClassLoader implements ClassLoaderHierarchy {
    private static final ClassLoader EXT_CLASS_LOADER;
    private static final Set<String> SYSTEM_PACKAGES = new HashSet<String>();

        def spec = new FilteringClassLoader.Spec([ 'allow.ClassName' ], [ 'allowPackage' ], [ 'allowPackagePrefix' ], [ 'allowPackageResource' ], [ 'allowResource' ], [ 'disallow.ClassName' ], [ 'disallowPackage' ])
        def filteringClassLoader = new FilteringClassLoader(parent, spec)
        def visitor = Mock(ClassLoaderVisitor)

        when:
        filteringClassLoader.visit(visitor)

        then:

    public ClassLoader get(ClassLoaderId id, ClassPath classPath, @Nullable ClassLoader parent, @Nullable FilteringClassLoader.Spec filterSpec) {
        return get(id, classPath, parent, filterSpec, null);
    }

    @Override
    public ClassLoader get(ClassLoaderId id, ClassPath classPath, @Nullable ClassLoader parent, @Nullable FilteringClassLoader.Spec filterSpec, @Nullable HashCode implementationHash) {

            .withClassLoaderStructure(classLoaderStructure)
            .build();
    }

    private static FilteringClassLoader.Spec getMinimalGradleFilter() {
        // Allow only certain things from the underlying classloader
        FilteringClassLoader.Spec gradleFilterSpec = new FilteringClassLoader.Spec();

        // Logging
        gradleFilterSpec.allowPackage("org.slf4j");

        // Native Services

            antClasspath.add(toolsJar);
        }

        antLoader = classLoaderFactory.createIsolatedClassLoader("isolated-ant-loader", DefaultClassPath.of(antClasspath));
        FilteringClassLoader.Spec loggingLoaderSpec = new FilteringClassLoader.Spec();
        loggingLoaderSpec.allowPackage("org.slf4j");
        loggingLoaderSpec.allowPackage("org.apache.commons.logging");
        loggingLoaderSpec.allowPackage("org.apache.log4j");

        GroovySystemLoader compileClasspathLoader = groovySystemLoaderFactory.forClassLoader(classPathLoader);

        FilteringClassLoader.Spec groovyCompilerClassLoaderSpec = new FilteringClassLoader.Spec();
        groovyCompilerClassLoaderSpec.allowPackage("org.codehaus.groovy");
        groovyCompilerClassLoaderSpec.allowPackage("groovy");

        def value = instantiator.named(Thing, "value1")

        def spec = new FilteringClassLoader.Spec()
        spec.allowClass(Named)
        spec.allowPackage("org.gradle.api.internal.model") // mixed into the implementation
        spec.allowPackage("org.gradle.internal.state") // mixed into the implementation
        def filter = new FilteringClassLoader(getClass().classLoader, spec)
        def loader = new GroovyClassLoader(filter)

                builder.put(fileName, content)
            }
        }
        def transformed = transformer.transform(DefaultClassPath.of(jar), BuildLogic)
        def filtering = new FilteringClassLoader(getClass().classLoader, new FilteringClassLoader.Spec([Action.name, Instrumented.name], [], [], [], [], [], []))
        testClassLoader = new URLClassLoader(transformed.asURLArray, filtering)
        return testClassLoader.loadClass(cl.name)
    }

import org.gradle.internal.classloader.ClassLoaderSpec;
import org.gradle.internal.classloader.ClassLoaderUtils;
import org.gradle.internal.classloader.ClassLoaderVisitor;
import org.gradle.internal.classloader.FilteringClassLoader;
import org.gradle.internal.classloader.SystemClassLoaderSpec;
import org.gradle.internal.classpath.ClassPath;
import org.gradle.internal.classpath.DefaultClassPath;
import org.gradle.internal.reflect.JavaMethod;