/*
 * Copyright 2012-2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot.context.annotation;

import java.util.Set;

import org.springframework.beans.factory.Aware;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.context.annotation.ImportSelector;
import org.springframework.core.type.AnnotationMetadata;

Interface that can be implemented by ImportSelector and ImportBeanDefinitionRegistrar implementations when they can determine imports early. The ImportSelector and ImportBeanDefinitionRegistrar interfaces are quite flexible which can make it hard to tell exactly what bean definitions they will add. This interface should be used when an implementation consistently results in the same imports, given the same source. 
 Using DeterminableImports is particularly useful when working with Spring's testing support. It allows for better generation of ApplicationContext cache keys. 
Author:
Phillip Webb, Andy Wilkinson
Since:
1.5.0/**
 * Interface that can be implemented by {@link ImportSelector} and
 * {@link ImportBeanDefinitionRegistrar} implementations when they can determine imports
 * early. The {@link ImportSelector} and {@link ImportBeanDefinitionRegistrar} interfaces
 * are quite flexible which can make it hard to tell exactly what bean definitions they
 * will add. This interface should be used when an implementation consistently results in
 * the same imports, given the same source.
 * <p>
 * Using {@link DeterminableImports} is particularly useful when working with Spring's
 * testing support. It allows for better generation of {@link ApplicationContext} cache
 * keys.
 *
 * @author Phillip Webb
 * @author Andy Wilkinson
 * @since 1.5.0
 */
@FunctionalInterface
public interface DeterminableImports {

	
Return a set of objects that represent the imports. Objects within the returned Set must implement a valid hashCode and equals. 
 Imports from multiple DeterminableImports instances may be combined by the caller to create a complete set. 
 Unlike ImportSelector and ImportBeanDefinitionRegistrar any Aware callbacks will not be invoked before this method is called. 
Params:
metadata – the source meta-data
Returns:
a key representing the annotations that actually drive the import/**
	 * Return a set of objects that represent the imports. Objects within the returned
	 * {@code Set} must implement a valid {@link Object#hashCode() hashCode} and
	 * {@link Object#equals(Object) equals}.
	 * <p>
	 * Imports from multiple {@link DeterminableImports} instances may be combined by the
	 * caller to create a complete set.
	 * <p>
	 * Unlike {@link ImportSelector} and {@link ImportBeanDefinitionRegistrar} any
	 * {@link Aware} callbacks will not be invoked before this method is called.
	 * @param metadata the source meta-data
	 * @return a key representing the annotations that actually drive the import
	 */
	Set<Object> determineImports(AnnotationMetadata metadata);

}