Spring @PropertySource @PropertySources

@PropertySource represent add a property source file for our configuration that will determine where the properties will be read from.

@PropertySource("classpath:/mysql.properties")
public class MySQLAutoconfiguration {
    //...
}

# @PropertySource use Java8 repeating annotations feature`, which means we can mark a class with it multiple times:
@Configuration
@PropertySource("classpath:/annotations.properties")
@PropertySource("classpath:/vehicle-factory.properties")
class VehicleFactoryConfig {}

# Use @PropertySources to specify multiple @PropertySource configurations
@Configuration
@PropertySources({ 
    @PropertySource("classpath:/annotations.properties"),
    @PropertySource("classpath:/vehicle-factory.properties")
})
class VehicleFactoryConfig {}