Spring Annotation

@SpringBootApplication

• @EnableAutoConfiguration

• @Configuration

• @ComponenetScan

@configuration,

@Bean

This is being used for java based configuration and if you so not want spring ioc to manage life cycle , then make use of this.

By default, spring beans are eagerly loaded, so load it lazily, we make use of @Lazy

@ConfigurationProperties

@Value will retrieve data from application.propeties file. but if we want to retrieve it from other custom properties file, then we have to use @propertySource along with @Value

@pathvariable /v1/{id}

path variable is mandatory part of request in case id is missing 404 is issued-resource not found

@RequestPAram /v1/idbyparam?id=1 , id is optional ,so still your endpoint will work