src/SchemaAnalyzer.php
private function getParentRelationshipWithoutCache($tableName)
    {
        $table = $this->getSchema()->getTable($tableName);
        foreach ($table->getForeignKeys() as $fk) {
            if ($this->isInheritanceRelationship($fk)) {
                return $fk;
            }
        }

        return;
    }
private function getParentRelationshipWithoutCache($tableName)
    {
        $table = $this->getSchema()->getTable($tableName);
        foreach ($table->getForeignKeys() as $fk) {
            if ($this->isInheritanceRelationship($fk)) {
                return $fk;
            }
        }

        return;
    }
If this table is pointing to a parent table (if its primary key is a foreign key pointing on another table),
this function will return the pointed table.
This function will return null if there is no parent table.

@param string $tableName

@return ForeignKeyConstraint|null