JDBC: ResultSet.getObject(int, java.sql.Struct.class) fails for STRUCT column #900

Bug description

For a STRUCT column, DuckDB JDBC reports org.duckdb.DuckDBStruct as the column class through ResultSetMetaData, which extends java.sql.Struct, but ResultSet.getObject(..., Struct.class) fails with a conversion error.

Reproduction

Create a table containing a STRUCT column:

CREATE TABLE test_table (
    struct_col STRUCT(name VARCHAR, age INTEGER) NOT NULL
);

Execute a simple query:

SELECT struct_col FROM test_table;

The ResultSetMetaData reports:

DuckDBStruct implements java.sql.Struct.

However, attempting to retrieve the value using the standard JDBC typed getter:

Struct value = resultSet.getObject(1, Struct.class);

fails with:

java.sql.SQLException: Can't convert value to interface java.sql.Struct, SQL type: STRUCT

I am using ResultSet.getObject(index, Struct.class) because getStruct() is only exposed through the DuckDB-specific org.duckdb.DuckDBResultSet, rather than the standard java.sql.ResultSet interface.

Environment

• DuckDB JDBC: 1.5.6.0
• SQL type: STRUCT
• Java type reported by metadata: org.duckdb.DuckDBStruct
• JDBC type: java.sql.Types.STRUCT (2002)