Proper procedure for modifying JHipster Entities using JDL - jhipster

Question

I am trying out JHipster (version 6.4.1) using a Monolith and disk-based H2 database. I have created some entities in JDL and have the basic CRUD webpages working. Now that I feel comfortable with the process, I want to add fields and rename others. I figured I could simply update the JDL, re-import the JDL, start the application, and see the result of my changes. What I see is ValidationFailedException from Liquibase and the application throwing HTTP 500 errors due to database problems.
I have looked all over for guidance on the proper process for handling this seemingly common development scenario. Most of the places I have looked for guidance (such as https://www.jhipster.tech/creating-an-entity) discuss importing JDL as a one-time-only operation and do not discuss how to incrementally change and import the JDL.
I have tried a number of suggestions as seen on SO, such as not overwriting the changelogs, doing a liquibase:diff, and adding that to master.xml. This still causes the ValidationFailedException. In the master.xml I see the comment <!-- jhipster-needle-liquibase-add-changelog - JHipster will add liquibase changelogs here --> which leads me to believe that JHipster should be doing the heavy lifting, but I am just missing a step.
I am by no means a JHipster nor a Liquibase expert, but I want to learn. How I can perform simple entity updates without a huge hassle?
[Update with more detail]
After re-importing the updated JDL, I have managed to get rid of the DB Validation Errors by blowing away the database with rm -rf target/h2db/db.
I'm happy with my changes and feel like a commit is in order. What I see is
master.xml is unchanged
the changelog from the first JDL import has been modified to include the updates I made
If I understand how liquibase works, I would have expected
None of the existing changelogs would be touched
A brand new changelog file would be created that contained just the JDL changes I made this round
master.xml to have changed only in that it would contain an additional changelog entry, pointing to the file created in item 2
Am I misinterpreting how Liquibase represents evolution of the DB schema?

Answer 1

It appears that the page you referenced does have some instructions for updating entities. Farther down the page I saw this:
Updating an existing entity
The entity configuration is saved in a
specific .json file, in the .jhipster directory. So if you run the
sub-generator again, using an existing entity name, you can update or
regenerate the entity.
When you run the entity sub-generator for an existing entity, you will
be asked a question ‘Do you want to update the entity? This will
replace the existing files for this entity, all your custom code will
be overwritten’ with following options:
Yes, re generate the entity - This will just regenerate your entity.
Tip: This can be forced by passing a --regenerate flag when running
the sub-generator
Yes, add more fields and relationships - This will
give you questions to add more fields and relationships
Yes, remove fields and relationships - This will give you questions to remove
existing fields and relationships from the entity
No, exit - This will exit the sub-generator without changing anything
You might want to
update your entity for the following reasons:
You want to add/remove fields and relationships to an existing entity
You want to reset your entity code to its original state
You have updated JHipster, and would like to have your entity generated with
the new templates
You have modified the .json configuration file (the
format is quite close to the questions asked by the generator, so it’s
not very complicated), so you can have a new version of your entity
You have copy/pasted the .json file, and want a new entity that is
very close to the copied entity