code: protected void checkFieldNotNull( Object fieldValue,
                                        String fieldName ) throws RepositoryException {
          if (fieldValue == null) {
              throw new RepositoryException(JcrI18n.requiredFieldNotSetInConnector.text(getSourceName(), getClass(), fieldName));
          }
      }
docs: Utility method that checks whether the field with the supplied name is set.
  
  @param fieldValue the value of the field
  @param fieldName the name of the field
  @throws RepositoryException if the field value is null