spring-boot | a newbie 's learning of spring-boot | Object-Relational Mapping library

I am trying to use JOOQ code generation from JPA Entity. I have already created a dedicated maven module where the code will be generated which has dependency on a module containing all entities as well code generation plugin with of jooq.

To add more clarify on project structure, here are the modules:(The names are made up but the structure reflects the current project i am working on)

I am using spring-boot 2.2.7.RELEASE

In the controller I want to get some values from external config file. But the application does not start even though the properties are available in the external config.

could you suggest how to load only specific properties from external config.

NOTE: I also tried spring.config.additional-location, and it is not working

Thanks

Controller

Starting with the sample from https://docs.gradle.org/current/samples/sample_jvm_multi_project_with_code_coverage.html (i.e., the code here https://github.com/gradle/gradle/tree/master/subprojects/docs/src/samples/java/jvm-multi-project-with-code-coverage ) and simply adding Spring Boot by changing application/build.gradle to

I am not able to generate log file using log4j2 spring boot 2.4, it's only printing logs in eclipse console. I already tried multiple solutions provided across web like: exclusions, renamed file to log4j2, changed properties multiple times (some are not using log4j.xx and some are not using it) not sure what to do ?

properties file:

I have a spring boot 2 app which connects to Mariadb database. This app runs in cloud foundry. It takes database connection properties from VCAP_* env variable.

App works fine and can connect to database. But, I have found out that app is not using hikari configuration specified in application.yml.

Can you please suggest what is wrong here?

build.gradle

I am new to spring boot and trying to figure out some of its working. Here I am getting Null Pointer Exception for the below implementation. I am not sure can we use @Autowire annotation for a Library project without a Main class. Maybe this sounds stupid,I believe we can do a @ComponentScan for the Library Project from a Service project that's created.My Question is looking at the below implementation is there any possibility to use annotation in the below library project, because Annotations are throwing NullPointerException for the below code?

Library

The below code is a library and it Doesn't have a Main Class

I have a Springboot project and I know I can send a application.properties file as a argument, but is this possible using a jar file?

I built my jar file using maven and in my application I have this piece of code that runs the programm if the user sent the argument run.

Is there any method that allows me to set the application properties if I receive it through argument? Or does the override of the file happens automatically as it does when I use the command mvn spring-boot:run -Dspring.config.location=your.properties

Without spring boot ,we must specify the detail of a data source,right?

I'm trying to run one test for my class "Sinus" (used to compute the sinus of a float), but when I try to run this test to generate my coverage report with Cobertura, it doesn't work and I really don't know why ! Dou you have advices or any explanation please ? (I use the cmd : mvn cobertura:cobertura)

-This is my test: