<?php

namespace CftfBundle\Form\Type;

use Doctrine\ORM\EntityRepository;
use Symfony\Bridge\Doctrine\Form\Type\EntityType;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;

class LsDocListType extends AbstractType
{
    /**
     * @param FormBuilderInterface $builder
     * @param array $options
     */
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('lsDoc', EntityType::class, [
                'label' => 'Choose Document',
                'choice_label' => 'title',
                'required' => true,
                'multiple' => false,
                'class' => 'CftfBundle\Entity\LsDoc',
                'query_builder' => function (EntityRepository $er) {
                    return $er->createQueryBuilder('d')
                        ->orderBy('d.title', 'ASC');
                }
            ])
        ;
    }

    /**
     * @param OptionsResolver $resolver
     */
    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults([
            'ajax' => false,
        ]);
    }
}

<?php

namespace CftfBundle\Form\Type;

use Doctrine\ORM\EntityRepository;
use Symfony\Bridge\Doctrine\Form\Type\EntityType;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;

class LsDocListType extends AbstractType
{
    /**
     * @param FormBuilderInterface $builder
     * @param array $options
     */
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('lsDoc', EntityType::class, [
                'label' => 'Choose Document',
                'choice_label' => 'title',
                'required' => false,
                'multiple' => false,
                'class' => 'CftfBundle\Entity\LsDoc',
                'query_builder' => function (EntityRepository $er) {
                    return $er->createQueryBuilder('d')
                        ->orderBy('d.title', 'ASC');
                }
            ])
        ;
    }

    /**
     * @param OptionsResolver $resolver
     */
    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults([
            'ajax' => false,
        ]);
    }
}

Change Choose Document form element to not required
Change Choose Document form element to not required

PW: made this change so I could use this form field in the tree view
