Grammar or Syntax Description

• The CONVERT TO CHARACTER SET clause in ALTER TABLE statements is not correctly parsed by JSQLParser.
• The parser treats the operation as UNSPECIFIC instead of the appropriate operation type.

SQL Example

ALTER TABLE test_table CONVERT TO CHARACTER SET utf8mb4;

Additional context

• Applicable RDBMS: MySQL 8.0
• JSQLParser: 5.0

The parsing succeeds without errors, but I believe it is necessary to add an appropriate CONVERT or AlterOperation type to handle this clause correctly.