https://github.com/plomino/Plomino/issues/713

demodb.json

{
    "design": {
        "formHide": {
            "elements": {
                "adult": {
                    "id": "adult",
                    "params": {
                        "description": "",
                        "edit_template": "",
                        "field_mode": "EDITABLE",
                        "field_type": "BOOLEAN",
                        "formula": "",
                        "html_attributes_formula": "",
                        "index_type": "DEFAULT",
                        "mandatory": false,
                        "read_template": "",
                        "title": "adult",
                        "to_be_indexed": false,
                        "validation_formula": ""
                    },
                    "title": "adult",
                    "type": "PlominoField"
                },
                "age": {
                    "id": "age",
                    "params": {
                        "description": "",
                        "edit_template": "",
                        "field_mode": "EDITABLE",
                        "field_type": "TEXT",
                        "formula": "",
                        "html_attributes_formula": "",
                        "index_type": "DEFAULT",
                        "mandatory": false,
                        "read_template": "",
                        "title": "age",
                        "to_be_indexed": false,
                        "validation_formula": ""
                    },
                    "title": "age",
                    "type": "PlominoField"
                },
                "is-adult": {
                    "id": "is-adult",
                    "params": {},
                    "title": "is-adult",
                    "type": "PlominoHidewhen"
                }
            },
            "id": "formHide",
            "params": {
                "null": false,
                "beforeCreateDocument": "",
                "beforeSaveDocument": "",
                "description": "",
                "document_id": "",
                "document_title": "",
                "dynamic_document_title": false,
                "form_layout": "<p><span class=\"plominoLabelClass\">adult</span><span class=\"plominoFieldClass\">adult</span></p>\r\n<p><span class=\"plominoHidewhenClass\">start:is-adult</span><span class=\"plominoLabelClass\">age</span><span class=\"plominoFieldClass\">age</span><span class=\"plominoHidewhenClass\">end:is-adult</span></p>",
                "form_method": "Auto",
                "hide_default_actions": false,
                "isPage": false,
                "isSearchForm": false,
                "onCreateDocument": "",
                "onDeleteDocument": "",
                "onOpenDocument": "",
                "onSaveDocument": "",
                "onSearch": "",
                "resources_css": "",
                "resources_js": "",
                "search_formula": "",
                "search_view": "",
                "store_dynamic_document_title": false,
                "title": "Hide When"
            },
            "title": "Hide When",
            "type": "PlominoForm"
        },
        "resources": {}
    },
    "id": "demodb"
}

demodb.xml

<plominodatabase id="demodb">
  <design>
    <element id="formHide" title="Hide When" type="PlominoForm">
      <id type="Products.Archetypes.Field.StringField">formHide</id>
      <onCreateDocument type="Products.Archetypes.Field.TextField"><![CDATA[]]></onCreateDocument>
      <onOpenDocument type="Products.Archetypes.Field.TextField"><![CDATA[]]></onOpenDocument>
      <beforeSaveDocument type="Products.Archetypes.Field.TextField"><![CDATA[]]></beforeSaveDocument>
      <onSaveDocument type="Products.Archetypes.Field.TextField"><![CDATA[]]></onSaveDocument>
      <onDeleteDocument type="Products.Archetypes.Field.TextField"><![CDATA[]]></onDeleteDocument>
      <onSearch type="Products.Archetypes.Field.TextField"><![CDATA[]]></onSearch>
      <beforeCreateDocument type="Products.Archetypes.Field.TextField"><![CDATA[]]></beforeCreateDocument>
      <FormLayout type="Products.Archetypes.Field.TextField"><![CDATA[
<p><span class="plominoLabelClass">adult</span><span class="plominoFieldClass">adult</span></p>
<p><span class="plominoHidewhenClass">start:is-adult</span><span class="plominoLabelClass">age</span><span class="plominoFieldClass">age</span><span class="plominoHidewhenClass">end:is-adult</span></p>
]]></FormLayout>
      <FormMethod type="Products.Archetypes.Field.TextField"><![CDATA[Auto]]></FormMethod>
      <DocumentTitle type="Products.Archetypes.Field.TextField"><![CDATA[]]></DocumentTitle>
      <DynamicDocumentTitle type="Products.Archetypes.Field.BooleanField">False</DynamicDocumentTitle>
      <StoreDynamicDocumentTitle type="Products.Archetypes.Field.BooleanField">False</StoreDynamicDocumentTitle>
      <DocumentId type="Products.Archetypes.Field.TextField"><![CDATA[]]></DocumentId>
      <ActionBarPosition type="Products.Archetypes.Field.StringField">TOP</ActionBarPosition>
      <HideDefaultActions type="Products.Archetypes.Field.BooleanField">False</HideDefaultActions>
      <HideInMenu type="Products.Archetypes.Field.BooleanField">False</HideInMenu>
      <isSearchForm type="Products.Archetypes.Field.BooleanField">False</isSearchForm>
      <isPage type="Products.Archetypes.Field.BooleanField">False</isPage>
      <isMulti type="Products.Archetypes.Field.BooleanField">False</isMulti>
      <SearchView type="Products.Archetypes.Field.StringField"/>
      <SearchFormula type="Products.Archetypes.Field.TextField"><![CDATA[]]></SearchFormula>
      <Position type="Products.Archetypes.Field.IntegerField"/>
      <ResourcesJS type="Products.Archetypes.Field.TextField"><![CDATA[]]></ResourcesJS>
      <ResourcesCSS type="Products.Archetypes.Field.TextField"><![CDATA[]]></ResourcesCSS>
      <excludeFromNav type="Products.Archetypes.Field.BooleanField">False</excludeFromNav>
      <elements>
        <element id="adult" title="adult" type="PlominoField">
          <id type="Products.Archetypes.Field.StringField">adult</id>
          <FieldType type="Products.Archetypes.Field.StringField">BOOLEAN</FieldType>
          <FieldMode type="Products.Archetypes.Field.StringField">EDITABLE</FieldMode>
          <isDynamicField type="Products.Archetypes.Field.BooleanField">False</isDynamicField>
          <Formula type="Products.Archetypes.Field.TextField"><![CDATA[]]></Formula>
          <FieldReadTemplate type="Products.Archetypes.Field.StringField"/>
          <FieldEditTemplate type="Products.Archetypes.Field.StringField"/>
          <Mandatory type="Products.Archetypes.Field.BooleanField">False</Mandatory>
          <ValidationFormula type="Products.Archetypes.Field.TextField"><![CDATA[]]></ValidationFormula>
          <ToBeIndexed type="Products.Archetypes.Field.BooleanField">False</ToBeIndexed>
          <IndexType type="Products.Archetypes.Field.StringField">DEFAULT</IndexType>
          <HTMLAttributesFormula type="Products.Archetypes.Field.TextField"><![CDATA[]]></HTMLAttributesFormula>
        </element>
        <element id="age" title="age" type="PlominoField">
          <id type="Products.Archetypes.Field.StringField">age</id>
          <FieldType type="Products.Archetypes.Field.StringField">TEXT</FieldType>
          <FieldMode type="Products.Archetypes.Field.StringField">EDITABLE</FieldMode>
          <isDynamicField type="Products.Archetypes.Field.BooleanField">False</isDynamicField>
          <Formula type="Products.Archetypes.Field.TextField"><![CDATA[]]></Formula>
          <FieldReadTemplate type="Products.Archetypes.Field.StringField"/>
          <FieldEditTemplate type="Products.Archetypes.Field.StringField"/>
          <Mandatory type="Products.Archetypes.Field.BooleanField">False</Mandatory>
          <ValidationFormula type="Products.Archetypes.Field.TextField"><![CDATA[]]></ValidationFormula>
          <ToBeIndexed type="Products.Archetypes.Field.BooleanField">False</ToBeIndexed>
          <IndexType type="Products.Archetypes.Field.StringField">DEFAULT</IndexType>
          <HTMLAttributesFormula type="Products.Archetypes.Field.TextField"><![CDATA[]]></HTMLAttributesFormula>
        </element>
        <element id="is-adult" title="is-adult" type="PlominoHidewhen">
          <id type="Products.Archetypes.Field.StringField">is-adult</id>
          <Formula type="Products.Archetypes.Field.TextField"><![CDATA[value = plominoDocument.getItem('adult')
return value == 'false' or value == '']]></Formula>
          <isDynamicHidewhen type="Products.Archetypes.Field.BooleanField">True</isDynamicHidewhen>
        </element>
      </elements>
    </element>
  </design>
</plominodatabase>