[Test] fix(bigquery): handle field named "f" in tableRowFromMessage

sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/TableRowToStorageApiProto.java

@@ -1137,7 +1137,6 @@ public static TableRow tableRowFromMessage(
       boolean includeCdcColumns,
       Predicate<String> includeField,
       String namePrefix) {
-    // TODO: Would be more correct to generate TableRows using setF.
     TableRow tableRow = new TableRow();
     for (Map.Entry<FieldDescriptor, Object> field : message.getAllFields().entrySet()) {
       StringBuilder fullName = new StringBuilder();
@@ -1147,10 +1146,24 @@ public static TableRow tableRowFromMessage(
       Object fieldValue = field.getValue();
       if ((includeCdcColumns || !StorageApiCDC.COLUMNS.contains(fullName.toString()))
           && includeField.test(fieldName)) {
-        tableRow.put(
-            fieldName,
+        Object convertedValue =
             jsonValueFromMessageValue(
-                fieldDescriptor, fieldValue, true, includeField, fullName.append(".").toString()));
+                fieldDescriptor, fieldValue, true, includeField, fullName.append(".").toString());
+
+        // Use setF when field name is "f" to avoid IllegalArgumentException with internal field
+        if ("f".equals(fieldName)) {
+          if (convertedValue instanceof List) {
+            @SuppressWarnings("unchecked")
+            List<TableCell> tableCells = (List<TableCell>) convertedValue;
+            tableRow.setF(tableCells);
+          } else {
+            // For scalar values, wrap in a TableCell and create a single-element list
+            TableCell tableCell = new TableCell().setV(convertedValue);
+            tableRow.setF(ImmutableList.of(tableCell));
+          }
+        } else {
+          tableRow.put(fieldName, convertedValue);
+        }
       }
     }
     return tableRow;

sdks/java/io/google-cloud-platform/src/test/java/org/apache/beam/sdk/io/gcp/bigquery/TableRowToStorageApiProtoTest.java

@@ -1860,4 +1860,39 @@ public void testCdcFields() throws Exception {
     assertEquals(
         Long.toHexString(42L), msg.getField(fieldDescriptors.get(StorageApiCDC.CHANGE_SQN_COLUMN)));
   }
+
+  @Test
+  public void testTableRowFromMessageWithFieldNamedF() throws Exception {
+    TableSchema schema =
+        new TableSchema()
+            .setFields(
+                ImmutableList.of(
+                    new TableFieldSchema().setType("STRING").setName("stringValue"),
+                    new TableFieldSchema().setType("FLOAT64").setName("f")));
+
+    // Create a DynamicMessage directly to test the tableRowFromMessage fix
+    Descriptor descriptor =
+        TableRowToStorageApiProto.getDescriptorFromTableSchema(schema, false, false);
+    DynamicMessage.Builder builder = DynamicMessage.newBuilder(descriptor);
+
+    // Set field values in the message
+    FieldDescriptor stringField = descriptor.findFieldByName("stringvalue");
+    FieldDescriptor fField = descriptor.findFieldByName("f");
+
+    builder.setField(stringField, "test");
+    builder.setField(fField, 3.14);
+
+    DynamicMessage msg = builder.build();
+
+    // Convert DynamicMessage to TableRow - this should not throw IllegalArgumentException
+    TableRow result = TableRowToStorageApiProto.tableRowFromMessage(msg, false, field -> true);
+
+    // Verify the conversion worked correctly
+    assertEquals("test", result.get("stringvalue")); // Field name is lowercase in the result
+    // For field "f", the value should be wrapped in a TableCell within a List
+    @SuppressWarnings("unchecked")
+    List<TableCell> fValue = (List<TableCell>) result.get("f");
+    assertEquals(1, fValue.size());
+    assertEquals(3.14, fValue.get(0).getV());
+  }
 }