title: Add WHERE IN clause to JPA Specification
body: <p>I'm trying to implement search functionality limited by IN clause:</p>
  
  <p>I want to implement search implementation with filter limitation:</p>
  
  <pre><code>    @GetMapping("find")
      public Page&lt;MerchantUserDTO&gt; getAllBySpecification(
              @And({
                  @Spec(path = "name", spec = LikeIgnoreCase.class),
                  @Spec(path = "login", spec = LikeIgnoreCase.class),
                  @Spec(path = "email", spec = LikeIgnoreCase.class),
              }) Specification&lt;Users&gt; specification,
              @SortDefault(sort = "login", direction = Sort.Direction.DESC) Pageable pageable
      ) {        
          return merchantUserService.getAllBySpecification(specification, pageable)
                  .map(g -&gt; MerchantUserDTO.builder()                   
                          .id(g.getId())
                          .login(g.getLogin())                        
                          .build()
                  );
      }
  
      @Override
      public Page&lt;Users&gt; getAllBySpecification(Specification&lt;Users&gt; specification, Pageable pageable) {
          return dao.findAllByTypeIn(specification, pageable, "MerchantUser");
      }
  </code></pre>
  
  <p>Repository:</p>
  
  <pre><code>@Repository
  public interface MerchantUserRepository extends JpaRepository&lt;Users, Integer&gt;, JpaSpecificationExecutor&lt;Users&gt; {
  
      Page&lt;Users&gt; findAllByTypeIn(Pageable page, String... types);
  
      Page&lt;Users&gt; findAllByTypeIn(Specification&lt;Users&gt; specification, Pageable pageable, String... types);
  }
  </code></pre>
  
  <p>What is the proper way to extend the specification with IN clause?</p>
  
  <p><code>specification.and(path.in(types))</code> path is a attribute but how to implement it properly?</p>