No-operation Hibernate Scanner

NopScanner.java

package com.javaetmoi.core.persistence.hibernate;

import java.util.Collections;
import java.util.Set;

import org.hibernate.jpa.boot.archive.internal.StandardArchiveDescriptorFactory;
import org.hibernate.jpa.boot.scan.spi.AbstractScannerImpl;
import org.hibernate.jpa.boot.scan.spi.ScanOptions;
import org.hibernate.jpa.boot.scan.spi.ScanResult;
import org.hibernate.jpa.boot.spi.ClassDescriptor;
import org.hibernate.jpa.boot.spi.MappingFileDescriptor;
import org.hibernate.jpa.boot.spi.PackageDescriptor;
import org.hibernate.jpa.boot.spi.PersistenceUnitDescriptor;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;

/**
 * No-operation Hibernate Scanner.
 * 
 * <p>
 * Do not scan for any classes, packages or resources inside a persistence unit. Return an empty
 * ScanResult. To use in conjunction with the Spring LocalContainerEntityManagerFactoryBean and its
 * setPackagesToScan method.<br>
 * A specific Hibernate properties has to be set: <code>
 * hibernate.ejb.resource_scanner=com.javaetmoi.core.persistence.hibernate.NopScanner
 * </code>
 * 
 */
public class NopScanner extends AbstractScannerImpl {

    public NopScanner() {
        super(StandardArchiveDescriptorFactory.INSTANCE);
    }

    @Override
    public ScanResult scan(PersistenceUnitDescriptor persistenceUnit, ScanOptions scanOptions) {
        final ResultCollector resultCollector = new ResultCollector(scanOptions);
        // Don't scan any archive
        return ScanResultImpl.from(resultCollector);
    }

    private static class ScanResultImpl implements ScanResult {

        private final Set<PackageDescriptor>     packageDescriptorSet;
        private final Set<ClassDescriptor>       classDescriptorSet;
        private final Set<MappingFileDescriptor> mappingFileSet;

        private ScanResultImpl(Set<PackageDescriptor> packageDescriptorSet,
                Set<ClassDescriptor> classDescriptorSet, Set<MappingFileDescriptor> mappingFileSet) {
            this.packageDescriptorSet = packageDescriptorSet;
            this.classDescriptorSet = classDescriptorSet;
            this.mappingFileSet = mappingFileSet;
        }

        static ScanResult from(ResultCollector resultCollector) {
            return new ScanResultImpl(
                    Collections.unmodifiableSet(resultCollector.getPackageDescriptorSet()),
                    Collections.unmodifiableSet(resultCollector.getClassDescriptorSet()),
                    Collections.unmodifiableSet(resultCollector.getMappingFileSet()));
        }

        @Override
        public Set<PackageDescriptor> getLocatedPackages() {
            return packageDescriptorSet;
        }

        @Override
        public Set<ClassDescriptor> getLocatedClasses() {
            return classDescriptorSet;
        }

        @Override
        public Set<MappingFileDescriptor> getLocatedMappingFiles() {
            return mappingFileSet;
        }
    }
}