code: protected List<String> getCandidateConfigurations(AnnotationMetadata metadata,
  			AnnotationAttributes attributes) {
  		List<String> configurations = SpringFactoriesLoader.loadFactoryNames(
  				getSpringFactoriesLoaderFactoryClass(), getBeanClassLoader());
  		Assert.notEmpty(configurations,
  				"No auto configuration classes found in META-INF/spring.factories. If you "
  						+ "are using a custom packaging, make sure that file is correct.");
  		return configurations;
  	}
docs: Return the auto-configuration class names that should be considered. By default
  this method will load candidates using {@link SpringFactoriesLoader} with
  {@link #getSpringFactoriesLoaderFactoryClass()}.
  @param metadata the source metadata
  @param attributes the {@link #getAttributes(AnnotationMetadata) annotation
  attributes}
  @return a list of candidate configurations