docs: @Override
      public List<DocumentRevs> getRevisions(String documentId,
                                             Collection<String> revisionIds,
                                             Collection<String> attsSince,
                                             boolean pullAttachmentsInline) {
          List<OpenRevision> openRevisions =
                  couchClient.getDocWithOpenRevisions(documentId, revisionIds, attsSince,
                          pullAttachmentsInline);
  
          // expect all the open revisions return ok, return error is there is any missing
          List<DocumentRevs> documentRevs = new ArrayList<DocumentRevs>();
          for (OpenRevision openRev : openRevisions) {
              if (openRev instanceof OkOpenRevision) {
                  documentRevs.add(((OkOpenRevision) openRev).getDocumentRevs());
              } else {
                  throw new RuntimeException("Missing open revision for document:" + documentId
                          + ", revisions: " + Arrays.asList(revisionIds));
              }
          }
  
          return documentRevs;
      }