title: ReactiveCouchbaseSortingRepository not allowing Pageable parameter in find query
body: <p>ReactiveCouchbaseSortingRepository in spring data for couchbase reactive not allowing <code>Pageable</code> parameter in <code>find</code> query</p>
  
  <p>I have pojo called <code>MyEntity</code> as shown below. 
  When I run the second find query below without <code>Pageable</code>, it returns correctly with response, but when I run with <code>Pageable</code> parameter , then it throws below exception while initializing the application.</p>
  
  <pre><code>Caused by: java.lang.IllegalStateException: Method has to have one of the following return types! [interface org.springframework.data.domain.Page, interface java.util.List, interface org.springframework.data.domain.Slice]
  </code></pre>
  
  <p>Though it should work as shown in the reference documentation as well as here for MongoDb</p>
  
  <p><a href="https://stackoverflow.com/a/46391830/5105808">how-apply-pagination-in-reactive-spring-data</a></p>
  
  <pre><code>public class MyEntity {
      @Id
      private String id;
      private Instant effectiveDateTime;
      private String createdBy;
      private Instant createdDateTime;
  }
  
  public interface EntityRepository extends ReactiveCouchbaseSortingRepository&lt;MyEntity, String&gt; {
  
  Flux&lt;MyEntity&gt; findByEffectiveDateTimeBetween(Instant start, Instant end, Pageable pageable) ;
  Flux&lt;MyEntity&gt; findByEffectiveDateTimeBetween(Instant start, Instant end) ;
  }
  
  
  
  
  
  Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'EntityRepository': Invocation of init method failed; nested exception is java.lang.IllegalStateException: Method has to have one of the following return types! [interface org.springframework.data.domain.Page, interface java.util.List, interface org.springframework.data.domain.Slice]
      at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1745) ~[spring-beans-5.1.4.RELEASE.jar:5.1.4.RELEASE]
  
  caused by: java.lang.IllegalStateException: Method has to have one of the following return types! [interface org.springframework.data.domain.Page, interface java.util.List, interface org.springframework.data.domain.Slice]
      at org.springframework.data.repository.query.QueryMethod.assertReturnTypeAssignable(QueryMethod.java:301) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
      at org.springframework.data.repository.query.QueryMethod.&lt;init&gt;(QueryMethod.java:86) ~[spring-data-commons-2.1.4.RELEASE.jar:2.1.4.RELEASE]
      at org.springframework.data.couchbase.repository.query.CouchbaseQueryMethod.&lt;init&gt;(CouchbaseQueryMethod.java:47) ~[spring-data-couchbase-3.1.4.RELEASE.jar:3.1.4.RELEASE]
      at org.springframework.data.couchbase.repository.support.ReactiveCouchbaseRepositoryFactory$CouchbaseQueryLookupStrategy.resolveQuery(ReactiveCouchbaseRepositoryFactory.java:222) ~[spring-data-couchbase-3.1.4.RELEASE.jar:3.1.4.RELEASE]
  </code></pre>
  
  <p>On further reading, it seems like a bug in spring data commons library.
  because the class <code>QueryExecutionConverters.java</code> in spring data from where it is checking the return type doesn't contain <code>Flux</code> or any reactive type in its list.</p>
  
  <p>Can somebody confirm whether its documentation error or code error in spring data commons.</p>
  
  <pre><code>ALLOWED_PAGEABLE_TYPES.add(Slice.class);
  ALLOWED_PAGEABLE_TYPES.add(Page.class);
  ALLOWED_PAGEABLE_TYPES.add(List.class);
  </code></pre>