You’ve created a circular dependency, or you're importing a module (tms-admin) that should not expose JPA Repositories to other modules like tms-core.

Spring Boot multi-module architecture best practices discourage cross-module repository usage like this.

A good solution here could be Restructure Your Modules.

• Move CustomerRepository and related entities (like Customer) into a new shared module, like TMS-data

• then update your module dependencies like:

  In core:

  <dependency>
      <groupId>com.TMS</groupId>
      <artifactId>tms-data</artifactId>
      <version>3.4.3</version>
  </dependency>
  

  in admin:

  <dependency>
      <groupId>com.TMS</groupId>
      <artifactId>tms-data</artifactId>
      <version>3.4.3</version>
  </dependency>
  

• Now both core and admin can use CustomerRepository without circular dependency.

  Do not forget to enable JPA repository scanning in your main application (usually in core):

  @SpringBootApplication(scanBasePackages = "com.TMS")

  @EnableJpaRepositories(basePackages = "com.TMS.customer.repository")

  @EntityScan(basePackages = "com.TMS.customer.model")

  Using CustomerRepository directly from tms-admin inside tms-core creates tight coupling and breaks modularity.

  It may work temporarily with tricks like manually adding @ComponentScan, but will always break Maven and clean builds due to dependency cycles.