code: public int isNullable(final int column) throws SQLException {
              final Boolean b = this.columnNullables.get(column);
  
              return (b == null) ? ResultSetMetaData.columnNullableUnknown :
                  (Boolean.TRUE.equals(b))
                  ? ResultSetMetaData.columnNullable 
                  : ResultSetMetaData.columnNoNulls;
  
          }
docs: {@inheritDoc}