code: @Override
      public StatementGroup convert(BELStatementGroup bsg) {
          if (bsg == null) {
              return null;
          }
  
          final StatementGroup sg = new StatementGroup();
  
          if (bsg.getName() != null) {
              sg.setName(bsg.getName());
          }
  
          final List<Statement> statements = new ArrayList<Statement>();
          final BELStatementConverter bsc =
                  new BELStatementConverter(ndefs, adefs);
          if (hasItems(bsg.getStatements())) {
              for (BELStatement statement : bsg.getStatements()) {
                  statements.add(bsc.convert(statement));
              }
  
              sg.setStatements(statements);
          }
  
          List<StatementGroup> childStatementGroups =
                  new ArrayList<StatementGroup>();
          if (hasItems(bsg.getChildStatementGroups())) {
              for (BELStatementGroup childGroup : bsg.getChildStatementGroups()) {
                  childStatementGroups.add(convert(childGroup));
              }
  
              sg.setStatementGroups(childStatementGroups);
          }
  
          return sg;
      }
docs: {@inheritDoc}