@Imports should be preferred to @ComponentScans

@ComponentScan is used to find which Spring @Component beans (@Service or @Repository or Controller) are available in the classpath so they can be used in the application context. This is a convenient feature especially when you begin a new project but it comes with the drawback of slowing down the application start-up time especially when the application becomes bigger (ie: it references a large JAR file, or it references a significant number of JAR files, or the base-package refers to a large amount of .class files).

@ComponentScan should be replaced by an explicit list of Spring beans loaded by @Import.

The interface @SpringBootApplication is also considered by this rule because it is annotated with @ComponentScan.

Noncompliant Code Example

@ComponentScan
public class MyApplication {
...
}

@SpringBootApplication
public class MyApplication {
...
}

Compliant Solution

@Configuration
@Import({
        DispatcherServletAutoConfiguration.class,
        ErrorMvcAutoConfiguration.class,
        HttpEncodingAutoConfiguration.class,
        HttpMessageConvertersAutoConfiguration.class,
        MultipartAutoConfiguration.class,
        ServerPropertiesAutoConfiguration.class,
        PropertyPlaceholderAutoConfiguration.class,
        WebMvcAutoConfiguration.class
})
public class MyApplication {
...
}

https://rules.sonarsource.com/java/tag/performance/RSPEC-4603

This ticket is mostly about investigating if we can improve the performance of the reference application modules startup by taking this into consideration. https://github.com/search?l=&q=org%3Aopenmrs+component-scan&ref=advsearch&type=Code