feat: Support aggregations by conversing expressions to specifications

[mhewedy]

No description provided.

[what-the-diff]

PR Summary

• Improvement to Expressions.java

  • This pull request enhances the Expressions.java file by incorporating a new tool - org.springframework.data.jpa.domain.Specification. This tool will bring better efficiency in how we handle and manage data.
  • It also introduces a new method named getSpecification(). This method provides additional flexibility and extensibility to the class.

• Increased Accessibility in ExpressionsRepositoryImpl.java

  • The accessibility of the ExpressionsSpecification class has been modified from private to public. This change enhances the usability of the class and allows it to be used across different parts of the program, increasing its value.

• Extension of ExpressionsRepositoryImplTest.java Test Cases

  • Several tools have been imported to assist with testing, specifically those related to structuring and querying data.
  • New field EntityManager entityManager; has been integrated, which helps in interacting with the database during tests.
  • Included a new test method testAggregations_by_convert_to_specifications_InJava(), enhancing the robustness of our testing, ensuring our application continues to deliver accurate and high-quality results.