(public api)
1 - create new ContentTypeCreateStruct
2 - add new field definition:
    - type: ezpage
    - name: test 
    ( leave all other values as default )
3 - attempt to save the class
4 - verify that an exception was raised:
    - eZ\Publish\Core\Base\Exceptions\ContentTypeFieldDefinitionValidationException: ContentType FieldDefinitions did not validate

eZ\Publish\API\Repository\Values\ContentType\FieldDefinitionCreateStruct Object
(
    [fieldTypeIdentifier] => ezpage
    [identifier] => ezpage
    [names] => Array
        (
            [eng-GB] => ezpage
        )

    [descriptions] => Array
        (
            [eng-GB] => This is an ezpage test
        )

    [fieldGroup] => 
    [position] => 15
    [isTranslatable] => 
    [isRequired] => 
    [isInfoCollector] => 
    [validatorConfiguration] => 
    [fieldSettings] => Array
        (
            [defaultLayout] => 
        )

    [defaultValue] => 
    [isSearchable] => 
)