Update Custom Property

Updates an existing CustomProperty.
The following fields can be updated:

• key
• label
• required
• default
• references

The same validations apply as when creating a CustomProperty.
Note, that the type of a CustomProperty cannot be changed, the reason for this is that the CustomObjectRecords
that have a value for the CustomProperty would be invalid if the type of the CustomProperty was changed.

Updates to the references:

• If a reference should be removed, the delete field of that reference should be set to true.
• If an existing reference should be updated, the id field of that reference should be set to the ID of the existing reference.
• If a new reference should be added, the existing list of references should be included in the payload and the new reference should be added to that list with the id and delete fields set to null.