old_contents: import icon from 'part:@sanity/base/calendar-icon'
  
  export default {
    name: 'dateTest',
    type: 'document',
    title: 'Date test',
    icon,
    fields: [
      {
        name: 'title',
        type: 'string',
        title: 'Title',
      },
      {
        name: 'justDefaults',
        type: 'date',
        title: 'Datetime with default config',
      },
      {
        name: 'aDateWithCustomDateFormat',
        type: 'date',
        title: 'A date field with custom date format',
        options: {
          dateFormat: 'Do. MMMM YYYY',
        },
      },
      {
        name: 'justARegularStringFieldInBetween',
        type: 'string',
        title: 'Some string',
        description: 'A string field in between',
      },
      {
        name: 'aDateWithDefaults',
        type: 'date',
        title: 'A date field with defaults',
      },
      {
        name: 'aReadOnlyDate',
        type: 'date',
        title: 'A read only date',
        readOnly: true,
      },
      {
        name: 'customPlaceholder',
        type: 'date',
        title: 'Date without custom placeholder',
        placeholder: 'Enter a date here',
      },
      {
        name: 'inArray',
        type: 'array',
        of: [
          {
            type: 'object',
            fields: [
              {
                name: 'date',
                type: 'date',
                title: 'A date field in an array',
              },
            ],
          },
        ],
      },
    ],
  }
  
new_contents: import {CalendarIcon} from '@sanity/icons'
  
  export default {
    name: 'dateTest',
    type: 'document',
    title: 'Date test',
    icon: CalendarIcon,
    fields: [
      {
        name: 'title',
        type: 'string',
        title: 'Title',
      },
      {
        name: 'justDefaults',
        type: 'date',
        title: 'Datetime with default config',
      },
      {
        name: 'aDateWithCustomDateFormat',
        type: 'date',
        title: 'A date field with custom date format',
        options: {
          dateFormat: 'Do. MMMM YYYY',
        },
      },
      {
        name: 'justARegularStringFieldInBetween',
        type: 'string',
        title: 'Some string',
        description: 'A string field in between',
      },
      {
        name: 'aDateWithDefaults',
        type: 'date',
        title: 'A date field with defaults',
      },
      {
        name: 'aReadOnlyDate',
        type: 'date',
        title: 'A read only date',
        readOnly: true,
      },
      {
        name: 'customPlaceholder',
        type: 'date',
        title: 'Date without custom placeholder',
        placeholder: 'Enter a date here',
      },
      {
        name: 'inArray',
        type: 'array',
        of: [
          {
            type: 'object',
            fields: [
              {
                name: 'date',
                type: 'date',
                title: 'A date field in an array',
              },
            ],
          },
        ],
      },
    ],
  }
  
subject: use calendar icon from `@sanity/icons`