BetterReflection\Reflection\ReflectionParameter::isOptional PHP Метод

    public function isOptional()
    {
        return (bool) $this->node->isOptional || $this->isVariadic();
    }

 private function assertSameParameterAttributes(\ReflectionParameter $original, ReflectionParameter $stubbed)
 {
     $this->assertSame($original->getName(), $stubbed->getName());
     $this->assertSame($original->isArray(), $stubbed->isArray());
     $this->assertSame($original->isCallable(), $stubbed->isCallable());
     //$this->assertSame($original->allowsNull(), $stubbed->allowsNull()); @TODO WTF?
     $this->assertSame($original->canBePassedByValue(), $stubbed->canBePassedByValue());
     $this->assertSame($original->isOptional(), $stubbed->isOptional());
     $this->assertSame($original->isPassedByReference(), $stubbed->isPassedByReference());
     $this->assertSame($original->isVariadic(), $stubbed->isVariadic());
     if ($class = $original->getClass()) {
         $stubbedClass = $stubbed->getClass();
         $this->assertInstanceOf(ReflectionClass::class, $stubbedClass);
         $this->assertSame($class->getName(), $stubbedClass->getName());
     } else {
         $this->assertNull($stubbed->getClass());
     }
 }