test(jdbc-v2): assert BFloat16 JDBC metadata is reported as FLOAT/Float

Add focused tests proving BFloat16 type information is reported correctly through the
JDBC metadata surfaces, per review feedback:

- JdbcDataTypeTests#testBFloat16ResultSetMetaData: ResultSetMetaData reports a BFloat16
  (and Nullable(BFloat16)) result column as Types.FLOAT / java.lang.Float, with the
  ClickHouse type name preserved (BFloat16 / Nullable(BFloat16)).
- DatabaseMetaDataTest#testGetColumnsBFloat16: DatabaseMetaData.getColumns reports a
  BFloat16 (and Nullable(BFloat16)) column as Types.FLOAT with the ClickHouse type name,
  plus a sibling Int32 contrast column.

The BFloat16 -> Types.FLOAT / java.lang.Float mapping already lives in
JdbcUtils.CLICKHOUSE_TO_SQL_TYPE_MAP; these tests pin it end-to-end. getTypeInfo BFloat16
coverage is already exercised by the existing DatabaseMetaDataTest#testGetTypeInfo.

Implements: #2279

Author: polyglotAI-bot

jdbc-v2/src/test/java/com/clickhouse/jdbc/JdbcDataTypeTests.java

@@ -610,6 +610,31 @@ public void testBFloat16WriteAsFloat() throws SQLException {
         }
     }
 
+    @Test(groups = { "integration" })
+    public void testBFloat16ResultSetMetaData() throws SQLException {
+        if (ClickHouseVersion.of(getServerVersion()).check(BFLOAT16_UNSUPPORTED_VERSIONS)) {
+            throw new SkipException("BFloat16 was introduced in ClickHouse 24.11");
+        }
+
+        // ResultSetMetaData must report a BFloat16 result column - and a Nullable(BFloat16) one - as
+        // java.sql.Types.FLOAT / java.lang.Float, with the ClickHouse type name preserved verbatim.
+        try (Connection conn = getJdbcConnection();
+                Statement stmt = conn.createStatement();
+                ResultSet rs = stmt.executeQuery(
+                        "SELECT CAST(1.5 AS BFloat16) AS v, CAST(NULL AS Nullable(BFloat16)) AS vNull")) {
+            ResultSetMetaData meta = rs.getMetaData();
+            assertEquals(meta.getColumnCount(), 2);
+
+            assertEquals(meta.getColumnType(1), Types.FLOAT);
+            assertEquals(meta.getColumnTypeName(1), "BFloat16");
+            assertEquals(meta.getColumnClassName(1), Float.class.getName());
+
+            assertEquals(meta.getColumnType(2), Types.FLOAT);
+            assertEquals(meta.getColumnTypeName(2), "Nullable(BFloat16)");
+            assertEquals(meta.getColumnClassName(2), Float.class.getName());
+        }
+    }
+
     // Text form of the exact BFloat16 whose bit pattern is {@code pattern}, suitable for use as a
     // SQL numeric literal. Non-finite patterns use ClickHouse's nan/inf/-inf tokens; every other
     // pattern uses the shortest round-trippable decimal of Float.intBitsToFloat(pattern << 16),

jdbc-v2/src/test/java/com/clickhouse/jdbc/metadata/DatabaseMetaDataTest.java

@@ -8,6 +8,7 @@
 import com.clickhouse.jdbc.JdbcIntegrationTest;
 import com.clickhouse.jdbc.internal.JdbcUtils;
 import org.testng.Assert;
+import org.testng.SkipException;
 import org.testng.annotations.Test;
 
 import java.sql.Connection;
@@ -146,6 +147,48 @@ public void testGetColumns() throws Exception {
         }
     }
 
+    @Test(groups = { "integration" })
+    public void testGetColumnsBFloat16() throws Exception {
+        if (isVersionMatch("(,24.10]")) {
+            throw new SkipException("BFloat16 was introduced in ClickHouse 24.11");
+        }
+
+        try (Connection conn = getJdbcConnection()) {
+            final String tableName = "get_columns_bfloat16_test";
+            try (Statement stmt = conn.createStatement()) {
+                stmt.executeUpdate("DROP TABLE IF EXISTS " + tableName);
+                stmt.executeUpdate("CREATE TABLE " + tableName
+                        + " (id Int32, v BFloat16, vNull Nullable(BFloat16)) ENGINE MergeTree ORDER BY id");
+            }
+
+            DatabaseMetaData dbmd = conn.getMetaData();
+            try (ResultSet rs = dbmd.getColumns(null, getDatabase(), tableName, null)) {
+                // Sibling Int32 column: a contrast case confirming only the BFloat16 columns are affected.
+                assertTrue(rs.next());
+                assertEquals(rs.getString("TABLE_NAME"), tableName);
+                assertEquals(rs.getString("COLUMN_NAME"), "id");
+                assertEquals(rs.getInt("DATA_TYPE"), Types.INTEGER);
+                assertEquals(rs.getString("TYPE_NAME"), "Int32");
+
+                // BFloat16 must be reported as java.sql.Types.FLOAT with the ClickHouse type name preserved.
+                assertTrue(rs.next());
+                assertEquals(rs.getString("COLUMN_NAME"), "v");
+                assertEquals(rs.getInt("DATA_TYPE"), Types.FLOAT);
+                assertEquals(rs.getObject("DATA_TYPE"), Types.FLOAT);
+                assertEquals(rs.getString("TYPE_NAME"), "BFloat16");
+                assertFalse(rs.getBoolean("NULLABLE"));
+
+                // Nullable(BFloat16): same SQL type, nullable, with the full ClickHouse type name.
+                assertTrue(rs.next());
+                assertEquals(rs.getString("COLUMN_NAME"), "vNull");
+                assertEquals(rs.getInt("DATA_TYPE"), Types.FLOAT);
+                assertEquals(rs.getObject("DATA_TYPE"), Types.FLOAT);
+                assertEquals(rs.getString("TYPE_NAME"), "Nullable(BFloat16)");
+                assertTrue(rs.getBoolean("NULLABLE"));
+            }
+        }
+    }
+
     @Test(groups = {"integration"})
     public void testSupportFlags() throws Exception {
         try (Connection conn = getJdbcConnection()) {