protected void add(Column defn) {
        if (defn != null) {
            Column existing = columnWithName(defn.name());
            int position = existing != null ? existing.position() : sortedColumns.size() + 1;
            sortedColumns.put(defn.name().toLowerCase(), defn.edit().position(position).create());
        }
        assert positionsAreValid();
    }
A implementation for {@link TableEditor} interface, which will used by {@link TableImpl} to create a {@link
TableEditor} object.
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/postgres-cdc/src/main/java/org/apache/inlong/sort/cdc/postgres/debezium/internal/TableEditorImpl.java