improvements-2.x-dev/modules/improvements_contact/config/schema/improvements_contact.schema.yml

contact.form.*.third_party.improvements:
  type: mapping
  label: 'Contact form advanced settings'
  mapping:
    page_title:
      type: label
      label: 'Page title'
    text_before:
      type: text
      label: 'Text before form'
    text_after:
      type: text
      label: 'Text after form'
    name_label:
      type: label
      label: 'Name field label'
    mail_label:
      type: label
      label: 'E-mail field label'
    subject_label:
      type: label
      label: 'Subject field label'
    message_label:
      type: label
      label: 'Message field label'
    submit_button_text:
      type: label
      label: 'Submit button text'
    name_placeholder:
      type: label
      label: 'Name field placeholder'
    email_placeholder:
      type: label
      label: 'E-mail field placeholder'
    email_subject:
      type: label
      label: 'E-mail subject'
    ajax_submit:
      type: boolean
      label: 'AJAX submit'
    ajax_submit_method:
      type: string
      label: 'AJAX submit method'
    dialog_title:
      type: label
      label: 'Dialog title'
    ajax_success_message:
      type: text
      label: 'AJAX success message'
    hide_preview_button:
      type: boolean
      label: 'Hide preview button'
    required_fields:
      type: sequence
      label: 'Required fields'
      sequence:
        type: string
        label: 'Field name'
    html_attributes:
      type: sequence
      label: 'HTML attributes'
      sequence:
        type: string

block.settings.contact_form_block:
  type: block_settings
  label: 'Contact form block'
  mapping:
    contact_form_id:
      type: string
      label: 'Contact form id'