why does my code throw a "bean not managed exception"?

Question

My code has been working fine with just a single repository package, until I began adding more repository & entity packages in my data source config class. The code failed with the exception: ... Error creating bean with name 'waecChemistryObjRepo' defined in com.example.resource.akademiks.waec.obj.dao.WaecChemistryObjRepo defined in @EnableJpaRepositories declared on AkademiksDbConfig: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class com.example.resource.akademiks.waec.obj.entity.WaecChemistryObj ... Error creating bean with name 'waecChemistryObjRepo' defined in com.example.resource.akademiks.waec.obj.dao.WaecChemistryObjRepo defined in @EnableJpaRepositories declared on AkademiksDbConfig: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class com.example.resource.akademiks.waec.obj.entity.WaecChemistryObj

Primary data source config class:

@EnableTransactionManagement
@EnableJpaRepositories(basePackages = {"com.example.resource.akademiks.waec.obj.dao",
        "com.example.resource.akademiks.waec.theory.dao", "com.example.resource.akademiks.waec.theory.answer.dao"},
 entityManagerFactoryRef = "akademiksEntityManagerFactory",
 transactionManagerRef = "akademiksTransactionManager")
public class AkademiksDbConfig {
    
    @Bean
    @Primary
    @ConfigurationProperties("spring.datasource.waecakademiks")
    public DataSourceProperties akademiksDataSourceProperties() {
        
        return new DataSourceProperties();
    }
    
    @Primary
    @Bean
    @ConfigurationProperties("spring.datasource.waecakademiks")
    public DataSource akademiksDataSource() {
        
        return akademiksDataSourceProperties().initializeDataSourceBuilder()
                .type(HikariDataSource.class).build();
        
    }
    
    
    @Primary
    @Bean(name = "akademiksEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean 
    akademiksEntityManagerFactory(EntityManagerFactoryBuilder builder) {
        
        return builder
                .dataSource(akademiksDataSource())
                .packages("com.example.resource.akademiks.waec.obj.entity")
                .packages("com.example.resource.akademiks.waec.theory.questions.entity")
                .packages("com.example.resource.akademiks.waec.theory.answer.entity")
                .build();
                
    }
    
    @Primary
    @Bean
    public PlatformTransactionManager akademiksTransactionManager(
            @Qualifier("akademiksEntityManagerFactory")
            LocalContainerEntityManagerFactoryBean akademiksEntityManagerFactory
            ) {
        return new JpaTransactionManager(akademiksEntityManagerFactory.getObject());
    }
    
}

Repository:

package com.example.resource.akademiks.waec.obj.dao;

@Repository
@RepositoryRestResource(collectionResourceRel = "chemistry", path = "chemistry")
public interface WaecChemistryObjRepo extends JpaRepository<WaecChemistryObj, Integer> {

service layers:

 package com.example.resource.akademiks.waec.theory.chemistry.service;

public interface WaecChemistryTheoryService {}

Service implementation:

 @Service
   public class WaecChemistryObjServiceImpl implements WaecChemistryObjService {
  @Autowired
 private WaecChemistryObjOptionRepo chemistryOptionRepo;

entity class:

package com.example.resource.akademiks.waec.obj.entity;

@Entity
@Table(name = "WaecChemistryObjAnswer")
public class WaecChemistryObjAnswer {

Other entities and repositories have been excluded.

Answer 1

The packages method takes a varargs parameter:

EntityManagerFactoryBuilder.Builder packages(String... packagesToScan)

You call it 3 times instead of passing 3 packages in a single call.

More generally: take advantage of auto-configuration and follow convention over configuration approach, as suggested in comments.