Well, in ValidatorTypeGuesser, the lines from 191 to 195 should add the maxlength attribute you are talking about. I don't really know why you are not getting it...

Ok i have tested it and with the following entity properites

    /**
     * @var string
     *
     * @ORM\Column(name="position", type="string", length=128, nullable=true)
     */
    private $position;

    /**
     * @var string

     * @ORM\Column(name="headline", type="string", length=128)
     * @Assert\NotBlank()
     * @Assert\Length(min="5", max="128")
     */
    private $headline;

form component generate the following html:

<input type="text" id="x_position" name="x[position]" maxlength="128">
<input type="text" id="x_headline" name="x[headline]" required="required" pattern=".{5,}">

So i suppose that maxlength attributte is added only when ORM\Column have length property defined widthut any constraint.

I have also tested $position with the following constraint:

    /**
     * @var string
     *
     * @ORM\Column(name="position", type="string", length=128, nullable=true)
     * @Assert\Length(max="128")
     */
    private $position;

and result is still

<input type="text" id="x_position" name="x[position]" maxlength="128">

So if I will use both min and max properties - maxlength is missing and pattern has only bottom limit defined.