TableEditorImpl.reorderColumn duplicates a column when moving a mixed-case column after the last column

[TimurRakhmatullin86]

Bug report

TableEditorImpl.reorderColumn(...) corrupts the column list when a column whose name contains an uppercase letter is moved after the current last column.

sortedColumns is a LinkedHashMap keyed by the lower-cased column name everywhere in the class — add() (put(defn.name().toLowerCase(), ...)), columnWithName() (get(name.toLowerCase())), removeColumn(), replaceColumn(), and the else branch of reorderColumn itself. Only the "just append" fast-path uses the raw name:

if (afterColumn != null && afterColumn.position() == sortedColumns.size()) {
    // Just append ...
    sortedColumns.remove(columnName);            // raw name, not lower-cased
    sortedColumns.put(columnName, columnToMove);  // raw name, not lower-cased
}
else {
    sortedColumns.remove(columnName.toLowerCase());     // else branch lower-cases
    ...
    newColumns.put(columnToMove.name().toLowerCase(), columnToMove);
    ...
}

Reproduction

Table with columns C1, C2, C3 (keys c1, c2, c3). reorderColumn("C1", "C3") (move C1 after the last column):

1. append branch is taken (afterColumn.position() == size);
2. remove("C1") removes nothing (the key is c1);
3. put("C1", ...) inserts a new key → the map now has 4 entries: [C1, C2, C3, C1] — C1 duplicated and never actually moved.

Expected [C2, C3, C1] (3 columns). With all-lowercase names the same call works, confirming it's purely the key casing.

Production impact (MySQL / MariaDB)

The Antlr DDL parsers preserve identifier case, and AlterTableParserListener.handleExitModifyColumn/handleExitChangeColumn call reorderColumn(column.name(), afterColumn). So:

CREATE TABLE t (Id INT, Foo VARCHAR(10), Bar INT);
ALTER TABLE t MODIFY COLUMN Foo VARCHAR(20) AFTER Bar;   -- Bar is the last column

duplicates the Foo column. TableSchemaBuilder then builds two Connect fields named Foo, throwing SchemaBuilderException: ... field name duplication and halting the connector on an otherwise-valid ALTER.

Fix

Lower-case the key in the append branch, mirroring the rest of the class:

sortedColumns.remove(columnName.toLowerCase());
sortedColumns.put(columnToMove.name().toLowerCase(), columnToMove);

Coverage

TableEditorTest.shouldReorderColumns() uses uppercase names but never moves a column to after the last one, so the append branch is untested. A unit test that moves a column after the last column exposes the 4-column result. PR with fix + test to follow.

[TimurRakhmatullin86]

PR: debezium/debezium#7895