* <p>
 * Classifiers are meant to be heuristic, determining the relevance on the best-effort basis.
 */
public interface StackTraceClassifier {

    StackTraceClassifier USER_CODE = new StackTraceClassifier() {
        @Override
        public StackTraceRelevance classify(StackTraceElement frame) {
            return StackTraceRelevance.USER_CODE;
        }
    };

    /**

            new InternalStackTraceClassifier(),
            StackTraceClassifier.USER_CODE
        ));
    }

    private final StackTraceClassifier stackTraceClassifier;

    public DefaultFailureFactory(StackTraceClassifier stackTraceClassifier) {
        this.stackTraceClassifier = stackTraceClassifier;
    }

    @Override
    public Failure create(Throwable failure) {

import javax.annotation.Nullable;
import java.util.List;

public class CompositeStackTraceClassifier implements StackTraceClassifier {

    private final List<StackTraceClassifier> classifiers;

    public CompositeStackTraceClassifier(StackTraceClassifier... classifiers) {
        this.classifiers = ImmutableList.copyOf(classifiers);
    }

    @Nullable
    @Override

import spock.lang.Specification

class DefaultFailureFactoryTest extends Specification {

    def "creates failure from a throwable with circular references"() {
        def factory = new DefaultFailureFactory(StackTraceClassifier.USER_CODE)

        def e0 = SimulatedJavaException.simulateDeeperException()
        def e = new RuntimeException("BOOM", e0)
        e0.initCause(e)
        e0.addSuppressed(e)

        when:

import javax.annotation.Nullable;

/**
 * Classifies various calls to JDK, Groovy and Gradle runtime as {@link StackTraceRelevance#INTERNAL}.
 */
public class InternalStackTraceClassifier implements StackTraceClassifier {

    @Nullable
    @Override
    public StackTraceRelevance classify(StackTraceElement frame) {
        return isInternal(frame.getClassName()) ? StackTraceRelevance.INTERNAL : null;
    }