Add ability to delete optional string values

[pjaydev]

According to the spec, the idShort attribute is an optional attribute for submodel elements. Nevertheless, after an idShort value has once been set, it can no longer be deleted. When just blanking the input field, still an empty string value will be stored for the idShort property on the generated JSON output.

In my use case, this caused two specific problems:

• As specified in Constraint AASd-120, elements, which are used as direct child of SubmodelElementList shall not have set an idShort. If an idShort was accidentally set, you will have to delete the whole element (tree) to restore conformity.
• The OpenAPI implemenetation requires a minimum of 1 character for idShort, if the field is defined. Hence the schema validator refuses a SubmodelElement object containing an idShort attribute with an empty string as value, as generated by the PackageExplorer.

EDIT: In fact the described problem does not only relate to ìdShort attributes, but rather more to each optional string-typed attribute you can find within the AAS schema. Further examples are all three string fields version, revision and templateId in the Submodel.administration field or the value attribute of a Property and possibly there are many more. I adjusted the issue title accordingly.

Thanks in advance.

[juileetikekar]

Hi @pjaydev,

Thank you for raising the issue !

We have developed a new feature "Fix and Finalize" which removes/fixes the issue with empty lists and empty strings. In additional to this, we are also working on more hints in such violations.

Meanwhile, I would like to request you to use this "Fix and Finalize" option to remove empty idShorts or such optional strings from the serialization.