code: public static WriteConcernResult unacknowledged() {
          return new WriteConcernResult() {
              @Override
              public boolean wasAcknowledged() {
                  return false;
              }
  
              @Override
              public int getCount() {
                  throw getUnacknowledgedWriteException();
              }
  
              @Override
              public boolean isUpdateOfExisting() {
                  throw getUnacknowledgedWriteException();
              }
  
              @Override
              public BsonValue getUpsertedId() {
                  throw getUnacknowledgedWriteException();
              }
  
              @Override
              public boolean equals(final Object o) {
                  if (this == o) {
                      return true;
                  }
                  if (o == null || getClass() != o.getClass()) {
                      return false;
                  }
  
                  WriteConcernResult that = (WriteConcernResult) o;
                  return !that.wasAcknowledged();
              }
  
              @Override
              public int hashCode() {
                  return 1;
              }
  
              @Override
              public String toString() {
                  return "UnacknowledgedWriteResult{}";
              }
  
              private UnsupportedOperationException getUnacknowledgedWriteException() {
                  return new UnsupportedOperationException("Cannot get information about an unacknowledged write");
              }
          };
      }
docs: Create an unacknowledged WriteConcernResult
  
  @return an unacknowledged WriteConcernResult