docs: public void addColumn(ColumnSchema column) {
  
          String name = column.getName().name;
  
          if (findColumn(name) >= 0) {
              throw Error.error(ErrorCode.X_42504, name);
          }
  
          if (column.isIdentity()) {
              if (identityColumn != -1) {
                  throw Error.error(ErrorCode.X_42525, name);
              }
  
              identityColumn   = getColumnCount();
              identitySequence = column.getIdentitySequence();
          }
  
          addColumnNoCheck(column);
      }