code: public int setInitialValueFilter(final String initialFilterString) {
          final Filter filter = buildFilter(initialFilterString, getFilteringMode());
  
          if (filter != null) {
              final LazyQueryContainer container = (LazyQueryContainer) getContainerDataSource();
              try {
                  container.addContainerFilter(filter);
                  return container.size();
              } finally {
                  container.removeContainerFilter(filter);
              }
          }
  
          return 0;
      }
docs: Before setting the value of the selected distribution set we need to
  initialize the container and apply the right filter in order to limit the
  number of entities and save them in container cache. Otherwise, combobox
  will try to find the corresponding id from container, leading to multiple
  database queries.
  
  @param initialFilterString
  value of initial distribution set caption (name:version)
  @return the size of filtered options