Doctrine\DBAL\Schema\SchemaDiff generates foreign keys statments for new tables even if the database platform doesn't support them

<?php
$schema = new \Doctrine\DBAL\Schema\Schema();

// Doctrine\DBAL\Schema\Schema pode ser usado para criar representações do
// schema, como a criação de tabelas
$myTable = $schema->createTable('my_table');
$myTable->addColumn('id', 'integer', array('unsigned' => true));
$myTable->addColumn("username", "string", array("length" => 32));
$myTable->setPrimaryKey(array("id"));
$myTable->addUniqueIndex(array("username"));

// SQLite does not supports sequences.
//$schema->createSequence("my_table_seq");

// Clone just to test Doctrine\DBAL\Schema\Comparator
$fromSchema = clone $schema;

$myForeign = $schema->createTable("my_foreign");
$myForeign->addColumn("id", "integer");
$myForeign->addColumn("user_id", "integer");
$myForeign->addForeignKeyConstraint($myTable, array("user_id"), array("id"), array("onUpdate" => "CASCADE"));

$queries = $schema->toSql($conn1->getDatabasePlatform()); // get queries to create this schema.
$dropSchema = $schema->toDropSql($conn1->getDatabasePlatform()); // get queries to safely delete this schema.

var_dump($queries);
var_dump($dropSchema);


$comparator = new \Doctrine\DBAL\Schema\Comparator();
$schemaDiff = $comparator->compare($fromSchema, $schema);

$queries     = $schemaDiff->toSql($conn1->getDatabasePlatform());     // queries to get from one to another schema.
$saveQueries = $schemaDiff->toSaveSql($conn1->getDatabasePlatform());

var_dump($queries);
var_dump($saveQueries);
?>

array(2) {
  [0]=>
  string(71) "CREATE TABLE my_foreign (user_id INTEGER NOT NULL, id INTEGER NOT NULL)"
  [1]=>
  string(105) "ALTER TABLE my_foreign ADD CONSTRAINT my_foreign_user_id_fk FOREIGN KEY (user_id) REFERENCES my_table(id)"
}