docs: public SchemaColumn find(String tableName, String tableAlias,
              String columnName, String columnAlias) {
          SchemaColumn col = new SchemaColumn(tableName, tableAlias,
                  columnName, columnAlias);
          int index = findIndexOfColumn(col);
          if (index != -1) {
              return m_columns.get(index);
          }
          return null;
      }